My Sony has a DVD recorder and also a 250gb hard drive.
I'll be honest here, I've used the DVD recorder about twice in 2 1/2 years, but I use the HDD side of things all the time.
I find it very, very useful. We even record programs with adverts, then start watching the beginning of the program about 15 minutes after it has started (HDD is still recording while we're watching the beginning).
This means we can skip all the ads, and catch up with 'real time' by the end of the program...It's great.
Also, it's my only source, and I find the DVD playback to be very good. Upscales to 1080i/720p (which is the max for my TV)
I believe the Sony RDR-HXD860 is the current fave, and if it's as good as my 910 I'd recommend it without hesitation.
A/V: Sony KDL-V40A12U & BDP-S350, BT Vision, Onkyo TX-SR875, B&W MT-30 7.1, QED audio cables, Russ Andrews power cables.
Hi-Fi: Arcam CD72T & A65+, B&W 602S3, Partington stands, Grado SR125, Kimber I/Cs, QED speaker cables, Russ Andrews power cables.