For what it's worth, I've decided to go with the Cannondale. Or at least ask the shop to order an Adv 3 or 4 in my size, presumably no obligation. They only had the Adventure 5 in my size, so I tried it and it fits well enough. I believe the frames are identical, and the components, though different, are the same size. It's the sealed suspension on the Adventure 3, which I presume means less mainenance, that's making me lean towards it over the 4.

I thought I'd prefer a model with trigger shifters, since that's what I'm use to, but all the ones I tried have the up and down levers far apart, so that I can't comfortably reach them both. (I have small hands, while my current bike has the levers next to each other.) I'm still concerned about the twist shifters, but figure it's now a toss-up between them.

I can point at little things that are largely in favor of the Cannondale, but I don't know if they're real or just rationalizations. In the end, it's the attitude of the owner of one particular LBS with regard to both fitting and training that's driving my choice.