My advice would be to get out and handle one before you buy. As a full-sized pistol they can be a handful, so if you have smallish hands it might be uncomfortable to shoot. Other than that, the Glock 20 is a nice pistol.
I'm not sure about the other guy but I never put an ounce of thought into a Glock 20 until I shot one and the recoil really isn't squat, at least not with whatever ammo was in there at the time (which was 10mm but didn't pay attention otherwise). My impression was .45 recoils more noticeably but maybe I was shooting some weak ammo.