This. You're going to be able to get a SB66 carbon for much less than the M6 and last I checked the "old fashioned" 26" wheels still roll pretty dang well.....may even have a few advantages still over the 27.5" (gasp, did I really say that out loud??).Love my 66c and you can't argue with the price of them at backcountry 30% off. Save some coin and go with an awesome brand like Yeti. But if money is no object then the Mach 6 does have the newer wheels and bling.