It really varies with load.
Since the G20 is so much heavier than a G22, shooting weak .40SW-grade 10mm is like shooting 9mm from a G17-- very mild a controllable, much less snap than .40 would normally have because the heavy slide really takes the edge off it.
Then you step up to medium power 10mm and things get interesting. Definitely a stronger recoil impulse, but the nature of it really varies. I really like the 200gr and 180gr loads. The 135s I don't care for, though a longer barrel helps both with ballistics and recoil.
The really hot 10mm loads (Underwood 135s) are definitely up there with the very stoutest .357 mag loads-- arguably even stouter.
It's nothing like .44mag, though. You can't really compare shooting guns of such vastly different weight.
I searched high and low for a Gen 4 before I bought my G20-- even had one on order for MONTHS, but I took the bird in the hand and bought a 3rd gen. Tired of waiting and getting jerked around.
I really prefer the grip and mag release on the Gen4s..
