I got the VLA II and returned it in favor of a DBX 166XL. I was using it on bass guitar and wanted a hard knee, but the VLA II only does really soft knee compression. As it ted out, the contour function on the 166xl turned out to be really advantageous for bass, becasue it allows the low end to pass uncompressed and be caught by the limiter. So it let's me compress the high end separately, without the high end compression being driven by the low end. I don't see that being advnatageous for tracking vocals, so I don't see any reason to choose the DBX over the RNC. I haven't used the RNC, but I hear such good things, I plan to get one eventually.
I think a lot of people like soft knee compression on vocals, so the VLA II might be good for tracking that. I knows Southside Glen raves about it for tracking.
Things I have read over and over again are that the VLA II is not transparent., and that it will color your tone. That makes some people really unhappy. But a lot of people pay $$$$ for neve preamps becasue they like the way it colors their tone, and some people apprently like the way the VLA II colors tone as well.
I didn't really perceive any tone coloration with the VLA II I had, but I wasn't really listening for it.