These have been covered in the past few months' issues of Cycling Active.
Dahon Mu Uno £480
Single speed, coaster brake, looks good, nice price. 80%
Brompton M3L £700
Steel, fold is "like a magic trick", looks great, geek chic, sophisticated ride, expensive. 90%
Strida SX £515
Not for shrinking violets, easy to manage folded, rides like "sitting astride a gigantic coat hanger", completely unlike a normal bike, belt drive is good but you can't ride out of the saddle, so no hill starts allowed, front wheel has a tendency to lift even when in the saddle on the flat, bulletproof and bonkers. 78%.
Giant Halfway 2 £400
Good price, good ride but disliked everything else (flimsy seat post, saddle was a horror, geared too low, no clip to hold it folded... and more). 77%
Mezzo I-4 £625
Clever, harder fold ("involves moving front to back to front to back..."), everything uses standard bits so no special tools needed for maintenance, anodised frame is resistant to damage, no breaking adjustment period unlike all of those above, confident and stable to ride, but why fit a chain tensioner on a hug-geared bike but still, potentially, the Brompton-killer. 92%
They also test the Airnimal Joey Sport £819 in a subsequent test. Love the way it rides, very sporty and a definite road bike with small wheelers rather than something which can unfold to make a bicycle. The only downside appears to be that it's a very distinctive bike, so not suitable for quiet types. 85%
Not exactly the models you were looking at but I hope it gives you a clue about what they liked and disliked and what you might look out for when making your own choice.
) but I can only agree with the weight. I love the extra gear range on the Jetstream, just wish it was still 9.0 kg!