I didn't have your particular makes and models but as far as D3.1 vs. D3.0, yes, I've also had fewer problems with a D3.0. It's like the D3.0 has been more stable and without issues.
Cox freely loaned me the Cisco DPQ3212 because I subscribe to Cox Voice and it's a combo Internet-telephone modem. The Internet portion of the combo modem had lots of issues, like yours, and eventually just died a few months later.
Instead of immediately replacing it, I installed my previous D3.0 (Surfboard SB6182) and it worked like a charm. In fact, I'm still using it 2 years later because it's been so reliable.
I don't know why. Perhaps a D3.0 is more tolerant of crappy service.
