My wife is 5'3" and resisted even demoing a 29er for a while. Then she demoed one and liked it. Now it's her primary bike. We shipped the bike for a riding vacation so she got back on the 26er... and hated it. Looks like we'll be getting rid of her old 26er bikes. Would love to get her on a 650b and am eyeballing the IM-196 for exactly that purpose.
On the other hand, I've got an old Scott Scale 26er which was my only bike for a while, and I recently resurrected it as a singlespeed. It's 18.6lbs, and once I got over the irrational fear that riding 26 would result in my immediate and painful demise, I'm actually having a bunch of fun on it. Mind you this is a local trail that is not terribly technical, and I'm still nowhere near as fast as I am on my FS 29er trail bike... but still, I'm having fun on a bike.
For me, though, there's nothing except 29er in my future.