I just recently moved and was forced to switch from FIOS to TWC. My old house was fully wired with ethernet so I had my Roamio and Mini wired via cat 5e. Ethernet really isn't and option for me in my new rental, so I was forced to give Moca a try.
My set up is as follows.
Motorola SB6141 modem
Apple Airport Extreme router
Actiontec Moca adapter
2 POE filters (one at POE and another at TA)
5 way 2ghz splitter at POE and a 2 way 2ghz splitter at TA
I have 5 coax cables coming from the POE splitter (living room, MBR, office, and two bedrooms that are unused)
Set up with the Roamio went very smoothly. I did notice that MLB.TV was a bit choppy at times and not nearly as perfect as it was with my ethernet setup. I then connected and set up the Mini. I kept consistatly having "Lost Connection" (V87) issues with my Mini.
I tried everything that tivo.com/help/v87 recommended, but I continued to have this issue. Thank you to everyone that recommended assigning a static IP address to both the Roamio and the Mini. I have no idea why this worked, but it did! MLB.tv is now working perfectly and more importantly, so is my Mini...no more issues at all!