I've done multiple streaming sessions from the Roamio Pro in my basement to the Premiere XL in my kitchen as well as the Premiere XL4 in my master bedroom and I've never seen any issues that I can think of like you're describing, Ziggie.
All of my Tivo units are on MoCA and all except the Premiere XL are using their integrated MoCA adapters.
The only possible issue has been a couple of pixelization/video artifacting issues, which I could chalk up to channel-specific issues as they've all been from a single channel of recent.
Roamio Pro (x2), Premiere XL4, Premiere XL, Mini
Sony S1, Toshiba RS-TX20 w/DVD burner, Tivo S2, S2 DT, S3, TivoHD, Premiere XL