We recently upgraded to the V6 and we love it. We have kept our TiVo so that we can watch the programmes we recorded earlier. We were told by the Virgin employee who arranged the installation that we could do this at no extra cost and the engineer demonstrated how to disconnect our new V6 and reconnect the TiVo. At this point we were happy.
Soon afterwards we tried to watch programmes from the TiVo but found that it had been disabled. We were told that we had been misinformed and in order to do what we planned we would have to pay for an extra box (we only wanted to use one box at a time because we only watch TV in one room). Fortunately Virgin customer services gave us a loyalty payment to fund this and both our boxes were activated.
Then we noticed that many of the programs we had set up on the V6 were deleted and some we had not set up appeared; the TiVo was likewise misbehaving. Only then did we realise that it was not enough to swap the cable between the two boxes, it was also necessary for the box you were not using to be unplugged. This is necessary because the (different) remotes are actually very similar and if both boxes are plugged in then both are affected whenever you use either remote.
I am not asking a question as such but I am posting this to help others in a similar position and to make sure more Virgin employees know how this plan actually works.