I carry Pistols from 8rd to 20 rd magazine capacity and it's not a consideration as to what i carry. As far as liability due to capacity?
Well, i suppose if you continue to pump rounds into a threat with a standard capacity Pistol after it has been neutralized, or then reload and dump more rounds into said threat, magazine capacity might be an issue.
If i feel so threatened that i have to use deadly force? How many rounds i expend to neutralize the threat depends on the situation.
I sure as hell want as many as i need, be it 1 or 20...and i prefer to have more than i "need" available.
Carry what's Legal, carry what you are comfortable with and Carry on.