Notice on the Compass bike text they say ahead (threadless) headset but it looks clear to me its threaded with the handlebar stem attached with a quill stem fitting. Not a problem but you can get a threadless folding bike stem where the handlebar stem attaches to the fork steerer tube which is what their text is stating but the images certainly don't show that. The Greenway bike is threadless. In theory threadless is a bit stronger/safer but I don't think its a big deal.
Greenway would provide pretty much no support. Total box shifter but the value of what you are getting is brilliant but servicing and adjustment is all up to the buyer. Great for many but not all. I've seen a Dahon bike in halfords sometime ago with poor welds, seem very expensive too with a freewheel for £400 thereabouts. Dahon is more a branding and marketing exercise often with the bikes made by other companies sometimes to Dahon's designs but often just a brand slap on an existing model. Their own factory looks pretty low tech and more of an assembly plant for parts built elsewhere and some very low tech frame manufacturing to supplement their bought in frames and so they can claim to be a full manufacturer nowadays. Their nuwave models are more innovative and take many of the ideas from their original bike design but whether they are popular is another matter. All seem to be single speed. The original Dahon folding bike below which they then dropped to make more conventional European style folding bikes. You can see the nuwave models use some of the strut designs with a very low frame height. I love the original Dahon folding bike I must say but doesn't represent a huge percentage of folding bikes sold in its day. For me the great folding bikes were the Dawes Kingpin and Raleigh Twenty. They set many of the rules for decent riding folding bikes back in the sixties and seventies.
I didn't say Dahon clone is a bad thing - in fact it's a good thing if it's close to a real Dahon. Yes, there are some horrible things with a Dahon label on them but the worst of them don't come to the UK. So, does anyone know what support (if any) Greenway provide?
With most bikes with near 50/50 fold I think you're supposed to tow it behind you, anyway carrying a 20" bike is cumbersome and the only bike that you would carry with ease for the size would be the Brompton but that's nowhere near in the running pricewise.
You say Dahon clone but Dahon often has their bikes made by other manufacturers. Maxcom bikes in Bulgaria for European bikes and lots of other companies around the world including Flying Pigeon and Fuji-ta in China. Often just a brand slap. Yes they have their own factory now but it only makes some of their bikes and there is a company in Taiwan that assembles their more premium bikes that I forget the name of. The Compass definitely looks like a fuji--ta bike which is a manufacturer (world's biggest bike manufacturer) that also manufactures for Dahon.