If we're talking about a "last mile or two" what's wrong with a conventional bicycle? These other things seem to be needlessly expensive and complex solutions to that problem.
The big problem with all of these though is they are all unpleasant in inclement weather and cold temperatures.
Conventional bicycles are bulkier than these other solutions, making them harder to carry onto whatever mass transit one is using. On Caltrain, for example, bicycles are restricted to a special car at one end of the train. On other systems like BART, bicycles aren't even allowed on many trains.
The other problem with conventional bicycles is that it's hard to go very far without getting sweaty -- depending on the weather, of course, and one's patience for riding slowly. It's nice to have power assist.
Folding bicycles can be compact enough to carry on any mass transit conveyance. The Metroboard is certainly quite compact and portable. Not sure about the Trikke.
I'd get a cheapo used bike and lock it at the station. Bike racks/poles are everywhere; personally, I think people carrying their Inspector Gadget $2000 foldabikes on the train are overestimating the utility of taking the same bike everywhere. As for getting sweaty, this is just the last mile we're talking about--if you get worked up on a 10 minute bike ride it's time for more exercise!
I think weather can be more of a perceived problem than an actual one, sometimes.
I ride a bike here in northern England. For two short rides of about 15-20 minutes each way, the chances of being rained on are pretty small; maybe ten times in a year? If you had a folding bike, then ten taxi rides on wet days might be a worthwhile yearly penalty.
The big problem with all of these though is they are all unpleasant in inclement weather and cold temperatures.