I’ve got a few of them, one for an AR, HK, CZ Scorpion & 10-22 … the only one that really isn’t “Plug & Play” is the one for the AR as you have to use the right buffer & spring … and it seems that there is something else but I don’t remember what off hand.
The others you can install and with just a little practice be shooting as advertised … the 10/22 is not only the least expensive to buy & shoot, it’s also the easiest to get proficient with.

Anyway, I’m thinking about getting the one for an AK but haven’t seen any reviews.
Any help out there in SiG land?

Sorry I can't help with the AK trigger. But I was wondering how your AR trigger feels. Mine is gritty. Is that normal with these? There is a huge difference between my Franklin trigger and my fostech trigger.

I lucked out with my BFAIII in my AR as I didn't need to swap any springs.

As for gritty, my trigger was no worse than the CMMG Mil-Spec trigger it replaced. It has smoothed out significantly since I've installed it, which is nice.