The G21 is a great pistol, exceptionally accurate and reliable. Mine's a Gen 3. I've heard from an exceptionally competant G21 shooter that I personally know and trust that he much prefers the G21 to the G41; the recoil characteristics of the G21 are better.
Unless you're trying for maximum velocity, I think the G21 makes eminent sense for most.
Of course, I do have a G34 holster that the G41 would fit...
Best, Jon