I bought the Onkyo just before christmas last year, fortunately it last only 5 weeks before a major corruption on the hard drive destroyed the unit (through standard usage I might add). I say fortunately because in a nutshell the system is rubbish, the whole implementation of the ripping/naming etc of the mp3s is slow (4x I think) and as already stated with compilations (or on fact any album where Gracenote gives different artists for different tracks) you end up with multiple albums. It has a crappy mono-colour screen which can only be read from about 1 foot away which tends to negate it being remote controlled)
Fortunately Richer Sounds offered me a full refund which I then used to purchase Sony GigaJuke NAS-SC55PKE for more or less the same price (£500), which IMO is perfect. Ripping is faster (16x and it will play the tracks during ripping which the Onkyo won't), it also comes with speakers (unlike the Onkyo), has iPod docking station, wireless unit (extra ones can be bought at about £200) for streaming to a different room. It has a nice big full colour screen (which can even be viewed on a TV). And you don't get multiple albums from compilation albums.
If I had a pound for every time the Onkyo crashed and had to be unplugged from the wall (a feat in itself in my house!) it would have probably paid for itself.
People complain that the Sony doesn't have full internet radio (only live365 and shoutcast), but who really uses internet radio? DAB is fine and it also gives all the DAB text (unlike the Onkyo).
Given that the two units are about the same price (if you shop around) IMO there is no comparison between the units and I have never been more happy for a £500 piece of kit to break than the day the Onkyo gave up the ghost. In a nutshell if you want a nice looking, easy to use, massively spec'ed unit to store your CD collection on then the Sony unit is perfect.
One last thing, my wife couldn't get her head round the Onkyo, whereas she has no problems with the Sony.