I would take the W6 over an 8500, ive only heard a 7500 and a w3 though so dont take my opion too seriosly. and theres so mayn other variables its hard to tell. what prices are you getting these for, comparably.
I'd take the w6v2 as well, but I wouldnt go as far as to call the 8500 a sloppy driver //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif