Well, I'm finally getting around to posting my review. Pictures will have to wait a bit until I get around to taking some. But they will come eventually.
To start, I'll get the negative stuff out of the way:
1: slight rattle from LED
2: copper sides of activation switch came off
3: black button greeble came off
4: menu confused me. 
5: no allen wrench
Otherwise, this thing is FANTASTIC!
I had originally planned to pick up a Prodigal Son eventually, possibly for a second or third saber (it was tied with an ASP Graflex). But when I saw that it came up on Etsy again after selling out, and I had just enough around to spare for it, I figured it was a sign and went for it. It was doubly a sign when this thing arrived on my birthday!
So I got to work since I was back in the lab at the time and actually got to open it. My one manager who was a big Star Wars fan was the first one to get to hold it and ignite it. I have to say it was WAY better than I imagined it to be.
To start, the weight on this thing is pretty good. Not too heavy, but it also doesn't feel fragile. I keep noticing that I'm gripping way further up on the neck than normal, but any way that you grip it, beside right on the activation box, it feels right.
The activation box itself is a mix of awesome and not so awesome. The great part about it, which I was a bit nervous about, is the way the card works. To start, that activation switch is VERY sensitive. Until you get the hang of not touching the card, you can ignite it with barely any effort. That turned out to be a little troublesome whenever I didn't know how to shut it off yet. So sue me, I was a bit too excited to stop and read the directions. As for people saying that the card would slide out or move around easily, I've noticed the chance of that happening is much reduced to what it was made out to be. I can slide the activation card up enough to expose the kill switch with no effort, but getting the card to come off of the activation box has been near impossible unless you force it off with the intent to get it out of there.
Some people mentioned that trying to spin a saber with an activation box as well as the activation card and thin neck was a bit of a difficult task that would "tear your hand up". Luckily, I haven't noticed that yet. If you keep the saber so the activation box is pointed toward your torso, you can maneuver the saber pretty well enough to never catch it. Plus, the way that the blade balances on the saber, if you're gripping it on the grip above the activation box, then the pivot point for any spins is right around the thin neck, keeping it in the curve below your thumb very nicely. It actually makes a really good axis to spin on and keeps you from hitting the box. I was pretty surprised at that too.
I can't really compare the way that you can spin a thin-neck saber to a solid saber since I don't have one, but I would assume that the thin-neck really seems to be a bonus for any type of spin if you have the activation box. It gives that extra half-inch almost of movement room to just miss the box hitting you. Without the activation box, the regular neck seems like it would be fine for spinning regardless. What this means for me is that I'll probably have to rethink how I'd be able to handle the Graflex if I get one.
At 5' 7.5", I have to admit that the 37" blade is hit or miss. It doesn't feel too long and it hasn't given me any issues where I feel like the balance of the saber is beyond a window of where the emitter is to where the thin-neck ends. As for trying to spin it, in bare feet and with low ceilings in my apartment, you can get a spin pretty well, but trying to cross your body does give you a bit of a shift in length at my height where it can hit the ground, my leg, or the ceiling a bit easier. I have yet to give it a try outside at any point, but I may try and head out to a not-so-populated area over the weekend to give it a shot and see how I can work with it without the narrow constraints of my crowded apartment. So, I'd say that for 5'9" and above, you're fine working with the 37", for below 5'7", I'd say to stick with the 32" if you want to try and do any type of spins or such. There's also the option of getting the 37" and just cutting it to the ideal length for you if you're below 5'9", but that's completely up to each person. I ordered a 32" blade with my Redeemer from the SF site, so I'll be able to revisit this in my review of that one when it comes in. [Note: you guys can hold me to revisiting this and making sure I do in case I forget to!]
To address the negatives:
As for the Greebles coming off, as everyone else on here noted otherwise, those are really easy to reattach, so I really don't need to cover those so much. The rattling of the LED is barely noticeable unless you focus on it really. I don't see a place for a LED retention screw on the saber, so that is likely one of the drawbacks to a thin-neck saber is that you can't really avoid that rattle if it starts. Regardless, I, personally, think it adds a little realism to the idea that there are actually functioning parts in there. Plus, if you have the sound set to "high" instead of low, there is NO chance you'll hear it when you're using the saber. That takes me to the menu part... Most of the menu being confusing is due to me not knowing how to set it or what to do with it without reading the directions. I'm still trying to decide which light effect (1-5) is best (If you want to go for a Kylo Ren type glow, use 3 or 4 for that unstable pulse). High sound is definitely better. I'm still playing with which "clash" sensitivity setting is best. Anything below 3 seems like it was way too stringent. So far, 4-6 seems to be the sweet spot for me, but I'm still trying to figure it out. I've gotten the feeling though that 7-9 is way too sensitive and just about anything that would trip the motion sensor registers as clash on those. As for the "motion" sensitivity, I'm getting the feeling that 5-7 is probably the sweet spot on that. Just out of habit in the past few times I've configured it, I've always tried to keep the motion sensitivity at least 1-2 levels above the clash sensitivity. The lack of the allen wrench was annoying, but I had a good set of standard and metric wrenches to figure it out and I'll likely just pick up a spare one to keep on the stand for the sabers when I get one.
Neutrals:
The blade "wobble" isn't nearly as bad as I thought it would be. One or two trips of tape might actually keep it from wobbling in the long run. Most of the time I've noticed the wobble is after I've swung it a few times or made contact, so it seems that the wobble comes from the screw finding a neutral position between fully tightened when you put it in and loosened. All in all, not that noticeable really unless you look for it, and likely easily fixable. The menu takes some figuring out, but, as I've learned, with playing around with the saber the day you get it, you're bound to pick up just what settings work best for you in a day or two. Plus, getting to play with the saber as "configuring it" is a pretty decent excuse to keep messing with it.
Positives:
The weight and feel are great. It seems amazingly balanced. The 12w LED is great (do not pull a ANH Luke move and look down the emitter of the saber while it is lit!). I did test to see how bright it was by accident and I had a grape-sized blotch in the middle of my vision for about 20 minutes after it. So the brightness is definitely great and seems to fill the blade amazingly (I can only imagine how nice it would make the day blades look). After messing with it for about an hour yesterday I put it in the charger to find that it only took about 2 hours to charge to full. So you'll definitely be able to get a couple days use out of it before you have to worry about charging. As for the kill key, as a lot of others have said, they are completely optional for the activation box sabers. With the lack of the illuminated switch, it doesn't drain battery. While you're getting used to the sensitivity of the switch, it's probably a great idea to keep it in so that you're not turning it on constantly without wanting to. There were no sharp edges or un-smoothed parts of the saber that I've realized so far. This thing is literally a phenomenal piece of work to look at as well as to handle.
This thing definitely went beyond my expectations to the point that I'm not sure what else I can put into words positively about it. If there are questions or things people want to know about that I didn't mention, ask them and I'll do what I can to answer them!
Again, I'll try to get some pics up soon!