what benefits do tubeless tyres bring to a 29er trail mtb? I have a 2014 Whyte T-129s and am considering converting the tires to tubeless. They are already 'tubeless compatible', so this should not be prohibitively expensive, but I am wondering whether this will really result in a better performance?
Well, the main advantages of tubeless is that you can run lower pressures (which comes with better shock absorption and thus control) with less risk of flats (though you should always carry a backup tube). I'm not entirely sure on where the truth is in regards to weight, but I don't think its important. The disadvantages are still having to carry a backup tube and the extra complexity of installing the tire.

In any case, if you have tubeless ready rims, its relatively cheap to try running tubeless on your own, so I think giving it a shot is the best way to convince yourself that its worth it or not.