Not sure about the Surly but they really don't seem to be something you want for multi-modal touring. They're more likely to discourage you from impromptu trips as there's going to be a fair amount of pre-planning involved.

With the BFs and Bromptons, it's mostly fold-and-go. I've only owned a 6-speed Brompton so I'd say they are built for your situation. I've heard good things about the Bike Friday warranty, so maybe you should ask around and make sure.

Just google "Brompton Touring" and I believe you'd be surprise at the many blogs that detail Brompton touring. Less so for Bike Friday, though I believe BFs have better upgrade paths, better ride quality and an amazingly quick fold.