I've read the first one many times, and I don't see a huge difference in terminology, CQ varies the bit rate to keep a consistent quality, and so does VBR, except that 2-pass VBR runs through the movie once to figure out where it can safely reduce the bit rate and still maintain the quality. How does CQ know where it can chop without doing something like that?
The second link was just starting to explain x-pass VBR and it ended with "To Be Continued"
Like I said, I can't test this without some really good sources. I only have captured VHS that I have to compress, since I don't yet have enough drive space to get a pristine capture. I also don't have a DVD drive... so experiences will be appreciated!