Anyone tried these?
http://www.tufo.com/colibri/

Is the weight too good to be true? Also if anyone has good experience using tubs for racing I wouldn't mind some advice. Ive had my years experience using stans and various tubeless setups and also tubular on the road but offroad especially on mtb makes me a little nervous ie rolling off the rim.
im also looking at going 29er for next year so want to get the lightest stiffest wheels possible.

I have been running those wheels for quite a few years now. They are really well made and appear to be very tough (I say 'appear' because I am using them for cross country and off-season riding, not all-mountain). The spec is very good, although the use of the centrelock hubs is self-limiting (although one of our Forum Members is manufacturing a crazy-light set of fully-floating, centrelock rotors that would look perfectly at home on a GP race bike). The Tufo tires are pretty good for the terrain that I ride, so I have been quite impressed with them. There are lots of choices, but I like Dugast or FMB with Racing Ralph or Ralph/Fred treads best.

whats the weight? you running 29ers

I'm running 26. They aren't quite as light as advertised, but are around 1260g.