Waiting on a regulator and other CO2 components, but hopefully I’ll start to have answers early next year. I’ll update the thread when I do.
They’re not really intended to be a sniper’s scope, but I’ve found G&P’s ACOGs to have very superior glass compared to other airsoft-grade sights. I’ve had a couple of clone Leupold 3.5-10x40 Mk.IVs and compared to those my old G&P 4x32 really was extremely nice.
4x is really all you’ll need in airsoft (you'll miss faffing with adjustable magnification and focus a lot less than you think you will), you don't get the fish-eye that seems endemic to airsoft-grade adjustable-magnification scopes, and the sight is extremely compact and basically indestructible. They're heavy and the eye relief is unforgiving, but they’re really good optically. I replaced my G&P with a real TA01NSN, and while the Trijicon is a lot nicer and has things the G&P didn't (like tritium illumination) the G&P was excellent and entirely adequate for airsoft.
G&P make a few different models; I had GP-035 - pretty much the most basic one. £85 for the sight, plus £7.50 for a polycarbonate lens and £7.50 for a killflash to put the lens in gives you an extremely rugged and high-quality BB-proofed optic for £100 - not bad. If I recall correctly a VisionKing shortdot is about £60 plus the mount and a lens protector, so there's probably only £20ish in it.
If you want to see how the ACOG looks on the shortest possible SRS, let me know - I can get a picture of mine.