Demoed a Giant Trance 650b, Trek Fuel EX 9.8 29er and a Scott Genius 730 650b on Saturday; wanted to keep them all but couldn't. If I could buy one of those bikes will be the Scott Genius because of its versatility even thou the Trance was the most fun of them.
When comparing wheel sizes found the 29er to be slower but capable of plowing thru stuff that the 650s will hit the cranks or get stuck . The 650s are quick and very responsive and that confirmed my thoughts about them, I can see a 650b in my future.
In recap, fell in love with carbon, 650b wheels and 2x10.