Im a newb to the piston uppers, but I have the SA on a 12.5" middy that was badly overgassed when suppressed even with other adjustable gas blocks. I chopped the barrel back to 11.9" and it is still overgassed suppressed even with the screw in full bleed off. I forgot to try restriction, but before cutting the barrel back it ran at ONE click out suppressed. Unsuppressed it runs fine at 7 turns out since I chopped it and ran at 8 turns out when it was still a 12.5".
Now BIG disclaimer. This is on a game gun. I have nothing milspec on it. I theorize the SA piston is made for mil spec style guns for reliable function when dirty with weak ammo etc. My set up is more like a Formula One race car with mud grips. I typically need only about half the gas of milspec to run such a gun so the SA with suppressor is just too much "function". I wish they would release a "performance" model with a smaller diameter piston and smaller outer dimensions plus a lightweight bolt carrier, but I honestly see very little market for such. Just oddballs like me shooting 3 gun.