I have a digifusion freeview box with hard disk, and this has two tuners in it. You can record digital two channels at the same time and even watch a previously recorded program.
As all Liteon users will know, recording to DVDs occasionally fails due to media problems So now I tend to initially record a program on the hard disk which is very reliable.
I then later record from the hard disk to a DVD at my leisure (if I want to save the program permanently. If the disk fails, I still have the original on the hard disk. I am also reducing the wear and tear on the Liteon as I am not recording as much on it as I used to.
One other really neat feature of the hard disk recorder is that it actually records anamorphically and hence can play back as 16:9 (for a widescreen tv) or 4:3 letterbox (for a normal TV). You can then select how you want it to be saved on the DVD recorder i.e. suitable for playing back on a widescreen or normal TV.
It would be nice if the liteon recorded anamorphically, but as far as I can tell it doesn't (if you set the source to widescreen and record it on the liteon, and then play it back on a 4:3 tv, it will always be squashed (tall thin people) despite the setting on Liteon - this means the recording is not anamorphic). The liteon can obviously play back anamorphic recordings though.