If you want to record and watch two channel you would need a dual LNB on the satellite as the box requires two cables but I think it should work fine with just the one cable unless I am mistaken?
Yeah I have a multiple LNB as I had multi-room and Sky HD so have 3 cables coming in.
Not sure if I should go for a FreeSat HD-R as it would only be 2 months of savings from Sky