Do you mean you are considering buying a high capacity 45, or the possibility of facing a high cap 45 when you have 8 shots of .357?
If the possibility of being attacked by 5 people was greater than average, I would opt to have more than 8 rounds available. Glock 19/23/32
I typically carry a subcompact Glock that's 9 + 1
Yesterday, I carried my Glock 38 (45 GAP) 8 + 1
9mm +P minimum. 40, 10mm or 45 preferred.