The guy at the shop did mention the cornering issues with a 29er vs 26. I'd be interested to hear from someone who's ridden both to see what they prefer.

They didn't have much in the way of Jamis MTBs (but I tried out a steel road bike), just Trek. But I did look at what I think was a Trek Marlin WSD from 2012. They seem to have discontinued this (and the Mamba WSD) in favor of the Cali, which is now their only WSD 29er. Weird.