As far as skill maintenance goes... run a few sets of double-taps from the holster, 3-4 round engagements from low ready and finish with some deliberate shooting at 50-75 feet. You can do this on about 30 rounds a week.
I am fortunate in that I can walk 200 yards to shoot, shoot anything I want any way I want, etc. If I had to drive & pay range fees fees, I would certainly shoot less often, perhaps once-twice a month, and I'd burn more ammo in a single session.
I carry both subject calibers, on and off duty. While I will always choose the larger bore, I doubt there's a substantial difference in their effectiveness.
“Nine-tenths of tactics are certain, and taught in books: but the irrational tenth is like the kingfisher flashing across the pool, and that is the test of generals. It can only be ensured by instinct, sharpened by thought practicing the stroke so often that at the crisis it is as natural as a reflex.” ~ T. E. Lawrence