Thanks for the reply wny!
I'm optimistic about the 47cm fitting. Even thought I'm only 5'2", I normally ride a size bigger frame than other women my height. I'm not really sure why, but I think it's related to the fact that my body type is somewhere between that of a 'typical woman' and a 'typical man'. My MTB has a 16" WSD frame, my commuter has a 16" MTB frame, and my roadie has a 49cm frame.
I checked out the geometry on my roadie frame. It has a 515mm top tube and a 110mm head tube (compared to 520/105mm for the 47cm Sherpa). Really, the two frames seem fairly similar, except the standover on the Sherpa is 12mm higher.
I think I'll head to my favorite LBS this week to talk to them about the Sherpa. I would have to order the 2011 model, which is kind of disappointing, because all the 2011s will have lower quality steel for the frames according to the Rocky Mountain website.
2010 Scott Speedster Limited/Bontrager Inform RL
2008 Cannondale Rush 2 Feminine/Terry Butterfly
2005 Cannondale F400/Terry Butterfly