Once call to comcast and they were able to change the SMC to "bridge mode" - which they explained is really pseudo-bridge mode. My Cisco router sits right behind the SMC, and network speeds and reliability have improved substantially. I recommend this to everyone
From what I can gather pseudobridge is pretty much what I did, except that I also DMZ'd my router address just to avoid any other weird surprises. No problems with the box since that one I had. I expect to replace it probably within a year since the sucker must be getting close to EoL by now.