Well, I've been shooting a Gen2 G17 for a long time. Tried to like a Gen 2 Mdl 22 and it just didn't give me the warm fuzzies. Personally I doubt there are many, if any, examples where a quality 9mm round failed that a quality .40 would have done the job. More bullets, a bit easier recoil, easier on the gun, a slight economic edge....for me the 9mm wins easily. If I had to carry a .40 I would, but given the choice I would (and did) go with the 9.