Thanks everyone! Two sets of wheels it is. I'll work on the 650 set later in life before I do the tour divide or something.

I'm not into big tires on the road. My normal commuter tires in the summer are 700x25 in a light-weight variety. Right now I'm running Vittoria Open Corsa SCs and they're great. My wider "winter" and touring tires are supposed to be light for their size (700x35 Vittoria Hypers) and I can still feel the difference, so I'm not really into the 35+ tires at all. It doesn't sound like the 650b dual use wheel-set would be for me.