said by mlord:
So no direct guaranteed connection there. That really just leaves a couple of possibilities then: (1) signal levels, except many people with issues report excellent signal stats, and (2) it depends upon the brand/model/version of equipment Rogers deploys at the local node (most likely) or at the CMTS (less likely).
Possibly also (3) the upstream modulation used for the upstream bonded channels. I have 16QAM up, but others have 64QAM up. 64QAM is a bit more work and a different code path on the modem.