Just got my first Mini setup and running yesterday and just wanted to say I had no problem at all!
Not sure if it matters but I set mine up in my home office/workshop with ethernet connection first and it worked flawlessly. In seeing other people's issue I decided to initially do the my office/workshop were I could sit down instead of the room were it was going to be installed (and hooked up by Moca) .
It downloaded it's update, went though the guided setup, found my Roamio and all was good.
Took it to the bedroom were it is going to be perfectly installed, disconnected the cable co box, attached all the Mini cables and it worked perfectly. I did have to go into the network settings and change the network for ethernet to MoCA but that's all had to do.
All is good and I made the wife very happy, she even posted of FB that better than flowers or chocolate for valentine's day, she got her own Tivo from her hubby.
Thank you Tivo, you make me look good!
Only problem, is now that I have done good, next time I will have to do better so I'm not sure what I will do.