I had a Strida for a few years; now my friend has it. It is probably the easiest bike for trains and escalators since it is a narrow stick that you can hug next to your body. It also rolls the easiest folded with it's parallel 16/18" tires, but you have to get the magnets just right and I added a velcro strap to eliminate the wheels coming apart when turning. The only drawback is you can't ride it fast due to its lawn chair posture and no standing on the pedals.

I use a Brompton often and it is OK for trains and escalators. I put 2 huge 4" roller wheels on it and pivot/move it by the raised seat. With a raised seat the bike will unfold so a velcro strap locks the front tire to the frame and all is kept tight rolling around, but since half the bike is offset, it always wants to tip over. You could get the roller wheel axle extender to solve this but I don't intermodal my bike enough to want to buy such an overpriced item. Seriously that thing probably costs $10-20 to make depending on volume. I don't want to roll by the bars because it is too big in a crowded train.

I do have a Dahon Dove (side folder) but I never use it anymore since a Brompton is better for me.