I'm in a very similar situation as you! I am a TWC internet subscriber (coax to 1st floor office) and a Dish Network TV subscriber (several coax jacks throughout the house, with a Hopper and 3 Joeys). However, I do believe that all coax connections flow through a single box outside, i.e. installed when the house was built, so there must be some sort of splitting there that sends the proper signal to the proper jacks.
That said, my need for Moca - particularly as I don't have a basement for relatively easy wiring - is to bridge my network from the office to the first floor living room on the other side of the house. The problem as I see it is that the coax jack in the living room is currently used for the Dish Hopper. That is, if I was all-in with TWC for both CTV and internet, I wouldn't foresee an issue.
This multi-band option looks appealing, but it doesn't appear to have hit the market yet. But, again, if the signals are split at the box outdoors as I suspect they are, I am hard pressed to understand how Moca is an option for me (since the signal would have to "jump" between the otherwise split cabling carrying the Dish signal on one and TWC internet on the other).
Of course, I stand to be corrected in my [limited] understanding of how Moca works, so thanks for asking the question, and I wish you luck in solving your dilemma!