I've run Moutons for about 20 years, generally in parallel with other stuff; the big question is: which one?
The older 1960's/70's f-frame models are now getting on a but, but are all capable of good performance and spares are available from Moulton Preservation (an adjunct to the Mouton Club). The general concept is still genius, with the integrated carrier mount and suspension both end. The 16 inch wheels limit tyre choice somewhat, but can be made to go well. The spacing of the swing arm limits the hub gear choice, but can be modified to accommodate more modern stuff, or there's a wealth of rebuilt 3 and 4 speeds available. I ran a recycled 4 speed with more modern brakes, new wheels etc. for a few years and it was a fine bike.
The AM range has existed since the 80's and variants are still in production now. This is the first of the space frame versions with small diameter triangulated tubes, 17 inch wheels and a number of variations including hub, 7 and 14 speed. They sell for large money now; the Japanese market in particular has driven prices up significantly. Again, spares available for everything, tyre choice is wider and there's optional upgrades if you want to go that way. Good handling, surprisingly quick and generally lovely. UI ran an AM7 for a few years; lovely bike, which I'd kept it!
The APB range was the 20 inch wheel Pashley made version. Lots of variations with a variety of gear trains and specials (such as the Land Rover). A far heavier frame, but a competent bike which has covered some serious miles on big expeditions. Never had one of these.
The TSR range - still current. A revised version of the Pashley frame, a lot lighter and again with a full range of gearing available, from a 2 speed to a Campag based 30 speed version. Biggest visual difference to the APB is that the location of the rear suspension unit has moved up the seat tube, improving strength ( I think that's what it's for..). I've had 2 of these - both worked extremely well.
New Series ( not so new any more) - a full space frame with torsion based elastic front suspension. A work of art, and prices never get below £4k, up to £16k for the double pylon. Interestingly, some reports suggest that the TSR is more useful as you can park it without fear, and it has more forgiving handling.
Naturally, there's a bunch of specials: the Bridgestone Moulton, a modern version of the F-frame; The elusive ATB, predecessor to the APB. Lots of obscure references - Jubilee; 'speed' versions, etc.
In short, a whole sub culture available, based on Moutons original concepts. I've always enjoyed them, they cause lots of conversation, they go well, handle luggage well, and are often very comfortable. I don't have one right now, but I will again!
Have a look at
http://www.moultonbuzz.com for the club website, and the factory site is at
http://www.moultonbicycles.co.uk