I'm a long-time user of Tivo, with two lifetime sub's, and know a bit about them (just fyi). I just purchased a new Bolt VOX, the agent said the only one available was the 500 Gb model, which I'll have filled in no time. I said, I can always expand it, and she said "Yes, you can."
I have a 3TB Western Digital WD30EFRX sitting around unused. I'm thinking of buying a Tivo, but only the 500GB version is within my budget, but 500GB is small for me. Is it possible to hook up a WD30EFRX to either a Tivo Roamio or Bolt via eSATA?