I have a 9 and a 10v. I cannot speak for the 9 because that one belongs to my wife and I don't move it up in NBI or OS X updates until I know for certain everything is going to be able to be made to work.
My 10v had problems with sound, OpenGL, Flash, and Safari after upgrading to 10.6.6, using NBI 20100616212351. So, with nothing to lose, I decided to try NBI 0.8.5Pre. The end result was that I had to install it twice, but the end result was exactly the same as NBI 20100616212351. No sound and problems with OpenGL, Flash, and Safari.
So, my opinion is that if you are going to update to 10.6.6 you might as well use NBI 0.8.5Pre.
I would be glad to hear anyone's suggestions for fixing sound and OpenGL. I have a feeling that Flash and Safari will behave properly once those two issues are tamed.