"How does this stuff do? Accuracy any good?"
GA makes very good 10mm ammunition, in my experience.
Their "remanufactured" 10mm ammo, using previously-fired brass, is reliable and can be had at a great case price ($180 for 1000rds). There have been occassional internet posts complaining of a bad primer here or there, or out-of-spec brass that caused a FTE. But by and large the reports are very positive - and that's across a range of calibers.
GA's "Shear Power Plus" (SPP) is "new" ammo using all new components, just like the big boys, but it's more affordable, at least in my area, than competing "premium" ammo. I believe shipping is free for orders over $500.
In my preferred caliber,
10mm Auto, GA uses the Gold Dot HP for its 10mm SPP, which is a great defensive bullet. They load both the 155gn GD and the 180gn GD.
Accuracy? Well, the group below, shot using the 10mm/180gn GDs, measures under an inch. (That's them in front in nickel cases).