This is one of the reasons I love the HK45 along with it fitting my hands perfectly. It seems to be a H&K thing though as my MP7 and MK23 both have the same type of ambi mag release and it looks like the USP does too.
I'd recommend asking people to have a test of their pistols at a skirmish if you can't make it to stores very easily. It's like I found the ergonomics of the Glock 19 and P226 to be dreadful, which is partly but not entirely to shooting left handed. For some people though this doesn't seem to be so much of an issue as a number of popular models of guns have things like mag releases in weird places or bad fire selectors.
I also still wonder why people can't get 50 metres out of TM pistols stock, it shouldn't require changing anything to achieve on Abbey or Green Gas with 0.25g BBs.