I really don't understand how someone can think that shorts stay in place better than bibs, but to each his own.

Currently I ride Pearl Izumi, Voler, ThreeFace, and Louis Garneau (all bibs). They are all fine on rides of 3+ hours long.

As far as pad placement, I think most of it has to do with pad size, not placement. My Garneau and Voler bibs have smaller pads, while the Pearl Izumi's and ThreeFace bibs have a larger pad (but I only notice it because the front of the pad ends around where my wang usually hangs out.

Maybe you haven't looked at the right "problem" ?? Methinks you might want to investigate new saddles?