said by DarkLogix:
Well I'd be careful some MoCA devices are on the same channel as HSI, though some aren't.
Retail MOCA adapters, like the ones you get from Netgear, etc., all operate at 1000mhz+, which keeps them well outside HSI ranges. I can say with first hand experience they work fine together, although I wouldn't hang a moca adapter in line with a modem just from a point of failure perspective.
Most configurations I've done isolate the modem drop in the home / business off a 2 way from the drop, and a MOCA filter is placed on the other leg. This was done just to eliminate a possible point of failure, technically you could put the adapter in line. A MoCA adapter would be tied in to a splitter after the 2 way to feed the other outlets.
The only time this would cause problems is if you forget the filter, install it improperly, or someday get Anyroom DVR service.