I ride a 26er and test rode 29er s-works epic and camber and they felt like they were rockets, the epic more so. So 29er is faster.
I then got back on my 26er and rode the same course, felt slower in a line, but easier to get through the tight stuff. So 26er is sometimes faster.
If my 12kg 26er was built to the same weight/spec as the 29ers I rode (sub 10kg) it would have been a better comparison. A new better (lighter, running gear etc) bike should feel faster, that's why we spend $$$$ upgrading. I'm not sold on 29ers yet, but if I had a squillion dollars and a massive garage I'm sure I would have one or more in amongst some 26ers. Choose your event, then choose your weapon.