The USB port on the Humax shouldn't make a difference. I only mentioned it because I was having trouble transferring files from the 5000T to USB (very very slow). I assume that if the transfer had completed it would be the same as from the other port.
Both Food and Quest are on DVB-T multiplexes (ie. not an "HD" multiplex) so that should not be a problem. I've just done a short test on these two channels - recorded on 5000T, moved to USB, renamed .recordings folder on PC, inserted into 2000T - and both recordings play normally.