I just had my first unexpected reboot tonight of my Roamio Pro. It happened a few minutes before 9PM. So my 9PM recordings had the first 3 minutes cut off. Luckily The Walking Dead and Homeland are repeated in a couple for hours.
The only thing different I did this evening was to use the TiVo app on my Nexus 7 with my Roamio. I'm guessing that caused some issue since I have not run into this before.
TiVo Mini x4
Roamio Basic OTA
53TB unRAID2--36TB unRAID3--32TB unRAID1a