I am thinking about going 650b on at least the front of my C'dale Rush. I have ordered a slightly longer rear shock and plan to modify the swing arm on the back to bring the back end up a bit. The result should be better roll over, slightly higher BB and steeper HTA and a little plusher in the back. It should be fun.
I am looking for an inexpensive 650b QR front wheel or rim. Deore hub/Sun eq27 rim is the price point I will be looking at if I go new. Even a cheap, used hub might be useful.