I pretty much agree with your write up, there are couple points, I think that are worth elaborating on:.
The satin finish applied to SP PBT SA sets, for example "Industrial SA" which I own, is a delightfully smooth and matt without being "bumpy," much smoother than Topre/Vortex PBT but not as smooth as shiny ABS. (Industrial SA is great because you can mix the keys into any set and they "look right;" the neutral grey and intermediate finish makes it a very useful set to own, if you like playing with layouts.) I have never seen a successful matt ABS without resorting to grippy textures - so with matt ABS on the chocolatier, you were pushing out the boat - to the edge of what's possible, imho.
Because SA double shots contain a much greater mass of material, they are much harder to manufacture without the odd imperfection, it has to cool down perfectly smooth not to warp or smudge. Tai-Ho use really thin plastic for a reason, it's cheap to make; it makes your keyboard much louder; which is good on alps sets, bad on cherry switches :-b (I kid... I kid...); for me, at least, it feels very chintzy... SP must have to run a fine line between the odd defect and keeping the prices competitive. This is why thick double shot went out of business in the 90s in the first place; thin, laser etched caps are always going to be more consistent. To get perfect sets out, we would be paying much, much, more. But, their customer support is amazing, so having them ship you an extra key here or there (for free) is a trade off worth making.
However, their shipping method is really sub standard. I suspect that it's due to being an industrial manufacturer that dealt with commercial quantities predominantly. This is why "group buys" had to be set up to get custom keycaps sets; it was the only way to meet MOQs. In the last couple years they set up a web store, so you can buy individual sets; but, with their build queue being slammed, they struggle to keep it filled up. (You can buy a rather nice high contrast Granite sets atm, btw) Their store (pimpmykeyboard) seems like such an afterthought to their main business. I don't think doing customer fluff, like stylish packaging etc, is in their corporate DNA tbh. Having dealt with purchasing between businesses, this is how SP treat you; you get exactly what you ordered, no more, no less and they have excellent customer support if you have issues. While certainly refreshing, the 0 fluff attitude, doesn't play well when you start to deal with more mainstream customers used to unboxing videos. When our hobby was a very niche activity, that was just fine, harcore hobyyists don't care about a nice box and will happily establish a personal relationship with their customer support person. With this going mainstream through sites like massdrop, it just feels budget to the average customer, they don't expect to build a relationship with customer support for the long term, they want a nicely designed box and no hassle. GMK has been much better at making this transition, imho.
I'm going to stop now... this has turned into a wall of text again.