I bought a Brompton while in
Europe and put thousands of miles on it in the
Med in daily use. If you are on a
small boat or are planning on going ashore with the bike in a
dinghy or lifting off the
boat (never store a bike off the
boat or you won't have it long) the small folded size makes the Brompton the top choice. Here in the US I ride it to a store, fold it up, put it in a
shopping cart and take it inside with me - no worries about theft. The Brompton folds smaller than any other popular folder, while unfolded the geometry is near the same as a full-size bike. Beware other small folders as they are really kids' bikes and are very hard to ride.
I have recently added a Swytch
electric motor kit and really like it. It provides a nice boost but is not enough to pull me up a hill without pedaling. If I were
buying new I would buy an electric Brompton, and for those with a Brompton I recommend adding a
motor - it is great fun. I had previously put a Mountain Drive planetary
gear in the bottom bracket, giving me a near perfectly-spaced 6 gears; I have been very pleased with it. However, with the motor a 3-speed is all that is needed.
There have been a couple of comments about wearing them out and needing
repairs, and
parts being difficult to find. Bromptons, like every other bike, do need
maintenance including occasional
replacements (e.g. tires,
cables, brake pads). That is only because they get used a lot. Well, 16 inch tires do wear out sooner than 27 inch tires but otherwise not any different from any other. Just as with other items on a boat you should carry a spares kit that includes likely replacement
parts, and never assume that a local store will have what you need. I don't see this as a disadvantage. Also, it really helps to know how to adjust and maintain a bike.
When I returned home I rebuilt my Brompton. I had the local seller replace the hinge pins in the bare frame as they were showing wear. I upgraded the brakes and headset, and replaced all of the cables. There are numerous small changes that I made over time to better fit the bike to my needs. But the basic frame and such has been robust. I also rebuilt my old '80s Trek touring bike with upgraded components - other than the folding hinges they were similar efforts that will eventually be needed with any well-used bike.
Greg