I love SP and was pretty broken up about this when I found out. We use SP keycaps exclusively on our SCRAMBLE [1] and while we could certainly switch to a different vendor and save money, the quality and experience wouldn’t be the same.
Having bought a few sets from Signature Plastics and a few other places, I have to say I'm impressed with their quality. I'm not sure exactly what it is, but they feel nicer than some other manufacturers I've seen. Hope they can find a good buyer.
The ASA (Akko SA) profile is a nice combination if you like the spherical aspect and central position of the marking without the odd height of SA profile.
I do agree that SA as a profile is weirdly high and that the keycaps wobble. It's designed for a very tilted layout, i.e. with the PCB tilted very much towards the user rather than more horizontally as is preferred by most modern users.
The original injection molding tool ended up a few kilometers from where I live. I always thought to give them a call and ask if I could touch the holy grail (and maybe make a few photos).
I love the R3 SA profile, where all the keys have the same profile as the third row of regular SA. Not as sculpted as regular SA, which I find too much.
It just launched last year so the sets aren't too widely available yet. I got a set last year and really love them. Full PBT double-shot, vibrant colors, and a very pleasing texture and scoop on the keys.
Fingers crossed they find a good buyer.
1: https://nullbits.co/scramble/