I purchased a VPI Classic 2 without knowing it had a Unipivot arm. It's a bit unsettling if you've never seen/used one. Seems to have no effect on sound quality.
The main advantage seems to be a bearing that never wears out. BTW, if you haven't seen a Unipivot tone arm, it's like an upside-down cup balanced on a nail.
I doubt I would have purchased had I known about it.