Extreme discomfort on your shoulders? Sounds like you either were wearing bibs that were too small for you or just really poorly made ones. There's no reason that the shoulder straps on bibs should dig into your shoulders unless you're trying to squeeze too much flesh into them. Nor is there any reason that a two inch wide strap made of wicking nylon material should make you overheat. A decent pair of bibs will have a lower cut in the front (some can come up fairly high over the lower abdomen) and a "racer back" design preferably with a mesh fabric.

Seriously, go to a brick & mortar bike shop and do the Goldilocks Test until you find ones that fit you. Some brands (European ones usually) run smaller so ignore the fact that you may have to go to a large or xtra-large.

Don't order them online blindly in an attempt to "try them out and see what the hype is about" until you know which brands work for you.