I have owned the Dahon Jack (same as Espresso) and while it was a nice bike its still a big lump when folded. I now own a Montague Bi-frame which is much more compact. The newer Montagues should also be much more compact when folded, especially when both wheels are removed, which doesn't take long to do. Slip the whole thing in a bag and you should be fine on train.
You can take non folding bikes on trains, possibly consider a non folding bike - remove the wheels and rotate the handlebars when storing it in your flat if you can find a corner for it to live in.