I just purchased a TiVo Roamio Pro. I'm planning to add a Mini as well, but I was surprised and disappointed to see that the TiVo will not allow me to bridge Wireless to MoCa, only Ethernet to MoCa. This makes no sense. I understand the need for MoCa to support streaming between the Mini and Roamio. But wireless is more than adequate to handle the bridge between MoCa and the Internet. It's got plenty of download bandwidth to handle guide downloads, remote programming, and even Netflix or other streaming. And for outbound TiVo streaming, whenever you enable that, outbound traffic speed of the cable or DSL modem will typically be the limiting factor.
As it turns out, I happen to have a Wi-Fi gaming adapter around that I can use to "trick" the TiVo into thinking it's on ethernet. But I should not need to do this. I sent them an email about this, I hope they fix this issue.