Re:
It's a good question that I can't answer easily.
The 650b is a large frame with 120mm forks, the 29er is a medium with 100mm forks. They have the same bars/stems/grips/saddles & pedals. 29er has a layback post.
The distance from saddle to bars is identical as is saddle height from the centre of the cranks. The 29er is more comfortable despite me being 6ft and Orange saying I need the larger frame.
The 650b has Nobby NICs and the 29er Continental X-King, I seem to prefer the Contis - or am I prefering the bigger wheels?
Can't fully get my head around the preference for the 29er, plus I wanted to prefer the 650b as it is a more complete build.
I plan to keep riding them both till the 29er build is finished, better forks/cranks/headset. Then rebuild the favourite with the XTR M9000 parts I am accumulating. I expect that decision in the summer.