I don't think I've ever found out what those "compatibility issues" are.
I know Comcast is among the worst offenders among cable companies with channel compression. Perhaps that interferes with how the IntelliStar 2 would receive/transmit information? Or... perhaps Comcast just uses a lot of non-standard/proprietary equipment?
I really do feel sorry for those with Comcast - one of the earliest cable companies to show the HD feed, but dead last when it comes to adopting the IS2. After having the IS2 available to me for the past couple of months, I certainly don't want to go back to not having it.