Just today we used a small M3B system ( 2tx and 1 Rx ) with sucess:

Picture the scenario:

Only One coax and one telephone cable on a wall. One side of the wall the Family room
tV, the other side, a bedroom TV.

Cannot run any new cables, HDBT baluns would not apply, and customer didnt want to have any equipment below the TVs. The sources needed to be in a remote closet.
So, we used the coax with a splitter, one port ñ feeding the M3B Rx behind the family room TV and the other feeding a super small Xfinity MoCa X1 box recessed behind the Bedroom TV. The Phone cable we used to carry IR from the Crestron processor from the Closet. That IR to control both TVs, the M3B Rx and rhe X1 Box. On the Closet, the Big X1 Master DVR and a Bluray, each one of them hooked up in a M3B Tx.

Worked flawlessly. I though we would have problems on the MoCa, but no...