Since your question is directed towards bib wearers, I'll chime in. I've never found shorts to be terribly uncomfortable or too tight around the waist, but the fit and comfort of bibs is very noticeable. They keep everything nice a snug while your standing or in the saddle pedaling for hours. I don't think it matters much for short rides of 20-30 miles, but 3 hrs or more in the saddle, the comfort and fit will start to show. For those doing shorter rides under a few hours it probably doesn't matter much.

I live in FL and can say they are no hotter than shorts. There isn't much material above the waist and since its wicking material, it helps to evaporate sweat. You do have to remove your jersey to take a crap, but that takes all of 10 seconds to take off and put back on. Peeing while in bibs isn't an issue for me.

Try a pair of bibs on a long ride, then do the same in shorts. See if you notice a difference.