Rolling resistance has nothing to do with it. The idea is simply that a tire with a larger outside diameter will roll over obstacles, within reason, with less difficulty than a smaller diameter tire. And in most cases this is true. If you're not an off road rider, you wouldn't understand. 29ers have disadvantages, too, such as weight and wheel strength (all other things being equal). Gary Fisher may have said the thing about a 2-3% advantage, but he's also said, "every bike is a compromise." Personally, I think a 2-3% performance advantage would be very difficult, if not impossible, to establish as fact. And I also think it's going to be very cumbersome for mfr's, retailers, and consumers to have another tire size (650B) added to the mountain bike market. Seems silly to me, all things considered. But I have ridden enough singletrack on a 29er to know that there are some very definite advantages with the bigger wheels. If you haven't ridden a 29er off road, maybe you should refrain from commenting-