OP,
I have the PI full leg bib tights and they're super warm. So warm, that I rarely wear them. I typically wear bibs with leg warmers instead. It's better to wear layers than 1 warm item. If it's <20 degrees, you'll be fine, but at 40 degrees, you eventually want to strip the warmers off when riding in the sun.

PI makes great stuff, so I don't think you can go wrong.