I have a Brompton which I bought some years ago when I went to buy a nut for the rear wheel of a sturmy archer equipped bike. I saw it in the bike shop window and bought it on the spot. It wasn't as much an impulse purchase as that sounds, because the bike I was fixing was a fake Brompton - a Merc, produced in China at first under some kind of license and then the parties fell out. I had originally wanted a Brompton before I bought the Merc, but when I went to the outlet near me who sold them he glibly informed me that I would have to wait about five months for him to be able to get his hands on one..... I suppose this would have been about 2004. I think they were struggling to keep up with demand at Brompton, and I saw this aluminium fake Brompton on Ebay at about half the price. I rode that fake about 4000 miles ( I had an odo on it) and then it was pretty worn out. The downtube broke at the top from hammering of the back subframe of the hinged rear end against the seat post clamp, and I resorted to drilling through the downtube and seat post and putting a bolt through because the clamp for the seat tube had broken off. This REALLY compromised the fold, but there was no other solution, given the alu construction. Can't really weld it as an amateur. I had hammered that bike mind. I went camping touring on it and rode it over speed bumps flat out on a regular basis (which was why the seat post clamp broke off).
The Brompton is a VASTLY better piece of engineering. Works better in every way than the fake, but I certainly got plenty of use out of the Chinese version.
I really like the Brompton folder, it is elegant, rides very well for a folder and it is incredibly versatile re storage, transport and functionality. I don't ride it where I am now living because of all the very steep hills in my current location, so I left it in storage in Newcastle. I tried riding it around here but I was mostly reduced to walking up hills with it. Plenty are 20%, so a three speed unless VERY much compromised by a low tooth count on the crank wheel is a no no for a man of my age and probably for most people really.
I have thought of converting it with a motor kit, but would not compromise the forks by grinding the dropouts which used to be needed when I was thinking about electrifying it. I think that there are other solutions now in front wheel motors with narrower axles. Not sure.