Have you used either of these machines?
For a start the Korg offers twice as many tracks (16 instead of 8) and it does not compress it's audio the way the VS does.
The Korg is much easier to use. I was able to get around one without the manual (touchscreen interface is great!). The VS on the other hand is just so damm tricky to use. However, over 100,000 users might not agree with me!!!!!!!!
Both offer high quality onboard effects but the Korg allows up to 8 insert as well as 2 master and 1 final effect to be used at once as opposed to the 2 master effects on the VS.
Both allow you to burn CD's direct from the unit but with the Roland you are forced to buy (and pay alot!!!!) for only their CD burner- no other burner can be used. At least Korg give you the option of using which ever burner is compatible with the D16.
However, I must say that the VS has a better build quality to it and it doesn't have the dreaded external power supply like the Korg does.
Both units allow you to record up to 8 tracks at once and both have virtual tracks.
However in the end, I would definetly choose the Korg because of it's ease of use, added fx capabilites and extra tracks.
However, if you only need 8 tracks than the VS is also nice- just be prepared to invest alot of time learning how to operate it! Cheers.