You can get a lot more vel with AA#9 vs AA#5 in the 10mm & at lower pressures.
I love AA#9 with 200gr bullets. With 180gr, AA#7 & BLueDot seem a better fit as does Longshot. You can reach 180gr/1300fps loads safely in a stock G20.
Just me maybe but I never got the accuracy or vel I wanted out of 800X & it is a huge PITA to meter, pass.