No we are not upgrading the Tivo yet - - It will be done after we have watched the recordings.
Shame VM (or the content provider) doesn't allow recordings to be transferred. The encryption & playback authorisation are compatible when STB are authorised on the same account, so any recording on the HDD, is technically playable on another STB with the same decrypt auth. (Yes I worked in the DVB CA inbdustry for 15 years !!).
Coax around the house is all either RG59, RG6 or equivalent. Connectors are Snap & Seal, so exactly the same as used by VM for drop cables !! I have a Viavi OneExpert for checking levels, MER, SNR, Ingress, etc. so it will work. Ethernet already patched through.