I use both techniques.
If i'm soloing, I pretty much exclusively use ADGC, so I actually rest my whole hand on BE keeping my fingers and thumb free for the other strings. I also notice, that if I'm sitting and playing, I tend to use floating thumb more, but when I'm standing, I tend to anchor more.
So, basically.....depends on what i'm playing.
Ooh, ooh, if I'm tapping I use my R wrist to mute.
Truckstop