Jhardwick1980: I own my cable modem (Motorola Surfboard/DOCSIS 3.0) and wireless router. I don't believe the Comcast supplied equipment applies to me, except for the potential addition of a supplied router/gateway for home security. I just want my main router to remain the hub of the operation. So is the additional home security router (Netgear presumably) directly connected to your modem or is it plugged into an available port on your router instead?
For what it's worth, I recently assisted a family member with their Comcast provided cable modem upgrade (self-install kit) to DOCSIS 3.0. I believe it was an Arris branded device which acts as a modem and wireless gateway "all-in-one". We ended up calling Comcast and they were able to send a signal and put the device in bridge mode. As a result, the modem was once again a transparent bridge between the coaxial cable and their Linksys router. Perhaps one of the newer Arris modems provided by Comcast may be the answer that you're looking for.