i have a Surly Long Haul Trucker that has 26" wheels on it, and I recently went from 1.5" tires to 2" ones. Surprisingly, it felt "faster" with the wider tires! Not sure if this translates to 650B but it went a long way towards validating Jan Heine's claims about wide tires being faster, in my mind at least.
__________________
Check out
www.djcatnap.com for articles on vintage Japanese & French bicycle restorations, components and history.