It sounds great... And I think it definitely has the edge over software in terms of raw sound.
But the sound gains, to the relative price, of the OB-6 makes it seem a bit ridiculous. Especially when you will be sweetening soft synths with a lot of plugins. So, you'll get a pretty close sound in the end. Not as good, but good enough for me...
That said, if someone has the cash and wants one, then why not? I mean, we all have certain things that we spend far too much cash on anyway.