24h format should not even be questioned !!!
Only in the USA is AM/PM used. Even there, military (and others, such as transportation Comagnies) only rely on the 24h format.
Alain, from Florida, USA
stay with 24hrs: this app is very useful on travel in different timezones. when i come to a location i will prepare my shooting well in advance. the 24hrs is more easy to adapt to diff timezones-.
Personal preference is 24 hour time. 12 hour time is obsolete.
However, since there are users wanting the 12 hour display just put it in a preference button