well I record at 192 khz @64 bit when I record on my comp... which is essentially beyond dvd audio quality... but by the time I'm done dropping it even to cd quality (44,100 @ 16 bit) I notice a SIGNIFICANT difference. Further compressing the file to mp3 format yeilds an even more intense difference... but to answer your question, I use vbr when I rip.
192 to rip, if I'm downloading I'll always take both the higher and low bit rates and store the better of the two.
The difference isn't noticable on most tracks but if the track has been produced well then i find that it's not only louder, the sound is much clearer and solid.
I much prefer the dynamics of a studio recording than any live recording although high fidelity wise the best track I currently have is a live acoustic version of Coldplay's Shiver (awesome soundstage).