of all the handguns i have shot (beretta 92 9mm, makarov .380, ruger sec. six w/.38s, hk usp 9mm, springfield 1911 .45, kahr k9 9mm) my kahr is the snappiest of the bunch.
I shot the 1911 for the first time last weekend. The guy i borrowed it from said "watch out, she kicks hard, keep a tight grip", and others have talked about .45s recoil like its quite rough...
after putting a few mags through it, honestly i didnt feel worried shooting it one handed with my weak hand. the recoil was very soft, not light, but soft compared to my kahrs quick snap. the weight of the fullsize 1911 probably helped with that.
im sure if you compared two exact guns shooting 9 and 45 that 45 would kick harder, but imo, not enough harder to be an issue. like others have said, its a different kind of kick.