No one has mentioned tne obvious problem with tightie whiteys under bibs...visible panty lines. Way not cool on a dude. I say go with the thong if you need a bit more support than th bibs provide.
I think the "panty lines" look way cleaner under riding shorts than jock straps showing through the Collegiate/NFL uniforms, but I'm not going to tell them that. I'll keep wearing the tightie "colored" under mine for now.