Thanks for the responses, so far. Here's the backstory for context...
My girlfriend and I are starting to talk about early retirement in five years and hitting the road for a big multi-year, multi-continent bike trip. She's got a Surly LHT (that could use a refresh) and I have a Cinelli Hobootleg (that needs to be ridden more). We can certainly use those bikes. But she's itching for a new ride and I'm thinking about those situations where we need to go multimodal with buses or trains or boats (we're trying to keep our footprint small and not fly) where there may be some restrictions on full-size bicycles. Or situations where we get a small room and want to bring the bikes inside with us without having them take up all the room. In those situations, a folding bike would help. So as long as there are no deal-breakers, I'm inclined to give folding touring bikes a try.
Slightly slower speeds doesn't bother us. I've heard some people talk about the lack of availability of 20" tires in remote places. And I've heard that the long cage derailleur hangs pretty close to the ground, which might be an issue on gravel or dirt. That's about it. That's why I was asking primarily for the opinions of former owners; to see if their reasons for going away from Bike Friday are things that we need to think about.
I figure that we'll need to choose our rides in the next 2-3 years and then do some shakedown trips to dial in our bikes and gear. Plus, I'm currently smitten with the new Bike Friday All-Packa. So that's spurring this discussion.