Yes, just about any router described as compatible with cable systems should work with Comcast. The list of "Comcast-supported routers, gateways, and adapters" are the devices Comcast distributes, or distributed in the past. It includes only a small fraction of the devices that will work with its internet service.
Yes, cable modems must be listed on the "mydeviceinfo" site, or Comcast will probably refuse to allow them to be used.
The forums modem and networking experts recommend avoiding combination modem-router ("gateway") devices, preferring seperate modems and routers. The most often recommended modems are the Motorola SB6120 or SB6121 and the Zoom 5341J. Routers are more variable, and depend more on your needs and budget.
Is there a modem listed on the "mydeviceinfo" page that is better than the surfboards?
Could you recommend a router for online gaming(no budget limit)?
And, what is the issue with the gateways?
1. Maybe not "better" than the Motorola SB6121...but newer in that rather than 4 downstream channels it offers 8...the Zoom 5341J is a pretty solid choice. Others here will certainly give it high marks.
2. There are a number of good routers out there, so this is only my recommendation: The Linksys EA4500 is a high quality router with a robust processor to make running multiple devices and demanding traffic efficient.
3. From what I see, there are 2 major issues with wireless gateways: First, you are stuffing a lot of circuitry in one box...heat can be an issue, and antenna array/placement is seldom optimal...Second, the user adjustable feature set is always limited and dumbed down. When it comes to gateways, it seems as if the router functionality is always the part that gets short changed. Comcast gateways seem to always have poor firmware loaded.