Given the choice of added pressure chamber or 20% greater capacity, I would take the extra shot in case I needed it. Also, with a snubby felt recoil is important for getting off a critical next shot, another area where the .327 would be an advantage. If I knew that I could get off the first shot perfectly every time, in a stressful condition, then the .357 makes sense. I do not know that I could ace the first shot every time so would rather put myself in a position where I could take more shots and get them off faster. But that is me and your experience may dictate a different approach.
No need to respond "Glock" cause we see that coming down the tracks like a 2 mile long locomtoive going 50Mph with the horn wide open!