Of course the 357 Sig has more recoil than a 9mm in the same gun. The 357 Sig pushes the same bullet weight ~200 fps faster than the 9mm. That means more recoil.
Ive shot my share of both, and never really noticed a difference. As I said earlier if I hand you a 31 or a 17, and you didnt know which it was, I seriously doubt you could tell by the recoil when fired.
The problem with paper ballistics is, yes, one has bigger numbers than the other, but no one seems to be able to translate the differences, into anything of substance. Other than the numbers are "slightly" bigger, on paper. Ive not seen anything that shows that the slight difference does anything more. 357SIG when tested in gel, performs to the same standards as everything else.
As much as some seem to want it to be, there are no magic bullets. And thats especially true with handgun bullets. The only proper response with ANY of them when used in a "stopping" capacity, is to continue to shoot until the threat is down. Hit a switch, and the target goes down with any of them. Miss that switch, try again, and continue until to do so until you do.
If you feel better using the 357SIG for carry, and want to practice with 9mm, thats makes the practice part easy, and a lot cheaper. Go all out 9mm, and you save more money yet.
I seriously doubt anything you shoot with either, is going to know the difference.