I don't want to come off like an ass or know it all but a safety should prevent the gun from going off, this includes *especially* accidental trigger pulls.
Call me old fashioned but I prefer a gun that I can keep cocked and locked. A heavy double action trigger pull is no substitute for a proper safety. Moreover, who wants a crappy double action trigger? I prefer a single action only or double action single action trigger.
Edit: I have large hands with long fingers. The glock finger indents do not match my hands and the grip feels square. But, AGAIN, that is just me. OP needs to see what fits and points naturally for him.
I think a glock is a great gun particularly if you don't plan on taking care of it. I put a lot of value on aesthetics and ergonomics and a one size fits all plastic gun falls short. The interchangeable backstraps are more of a gimmick than anything else. They can take a gun that fits good and make it fit great but they won't do much for a gun that just doesn't fit at all.