I helped my brother install his TiVo mini yesterday. It was pretty uneventful. We first put in a MOCA bridge since he did not have an ethernet drop. Then we installed the TiVo mini. The hardest part was getting the connections behind the TV that was wall mounted and we did not want to take it down. The mini booted up took about 15 minutes to set up. During the setup it asked if we wanted to use Ethernet or MOCA. We said MOCA, it went and found its address via DHCP, contacted the TiVo service and then downloaded the guide data.
It works really well. It is a touch slower on skip forward and back (we activated the instant 30 second skip). Aside from that it was hard to tell we were not at the TiVo.
It looks like it does everything in the box (guide, IPTV like Netflix, etc.). The only thing it seems to use the "master" TiVo for is a network disk.
We did dedicate a tuner to it.
All in all it was pretty fast and painless.
Since my brother was able to replace 2 HD DVR boxes with the TiVo XL4/TiVo mini he will save $33/month (17.50 per cable DVR vs the single $2 cable card for the TiVo). He will save the cost of the TiVo/Mini in under 3 years.