The info I've read on the X1 shows it does support some IP clients. If your scenario will be using the IP clients then I would expect the limitations would be based on the underlying infrastructure (moca, cat5/6, fiber, etc.)and the whole home dvr application(latency, etc.). To IP, it's just another packet and IP has been supporting "campus" enviroments with multiple buildings for years. I would think Comcast would use the fiber lan connection rather than moca in this configuration.