Each of my 622's has its own 500 gig for archiving, I have an old 80 gig drive I use to transfer between my two 622's on the rare occasion I want to watch something I've recorded in the Living Rm back in the theater.
I only use the small 80 gig for xfer betwen the two. When the DVR wants to erase/reformat I don't care because all that's on it is/are the two or three movies/shows I want to xfer.
Of course being able to just grab the Drive from the LR and plug it in in the Theater would be much better...
Better still, would be to xfer shows between the two Via ethernet through the network.