I'm also a user of unbiased engines, but i have to admit that if i knew vray well enough i would probably just use that. The big advantage for unbiased is the litle time is takes to set things up, wihtout needing to know too much technical stuff, but in return the render times are ridiculous big. Now the problem is that, in this CG business, we're always learning and evolving our skills and knowledge, with time beeing allways against us, so often we reach a point that we want the same quality (almost) with a fraction of the time and that's when we users, that ironicly always ask for simplicity, start studing and using more complex stuff that fit our new goals...
I have 2 friends that everyday remember me that no matter how good quality my unbiased render is, their Vray and mental ray stuff will allways look better (I'm talking really top stuff here). They don't even lose much more time than me setting a scene up (experience and material libraries compensate that) and in render times i don't have a chance either, especially if we're talking big print resolutions...Nowdays i'm using more and more biased methods for render and evolve my photoshop skills...some stuff is a pain but it's starting to pay off