Hmmm! Here we go again, people getting all negative over another of Mark's designs, when few have actually experienced it.
A few years ago I was privileged to attend a lecture that Mark was giving to the Institute of Structural Engineers, in Bath.
He brought along a Swivelhead (the IF prototype) a Strida and an early X-bike (the pre A-bike prototype)
I have folded and unfolded the Swivelhead, it was easy. But you all seem to be missing the point, the locking action of the Swivelhead catch pulls the frame into tension ( the way a Pedersen does when you sit on it) creating a very stiff frame that is also a very managable size, when folded, and which rolls very easily & comfortably. It was very nice & stiff to ride (unlike the X-bike, with it's tiny wheels and cable operated steering!)
I for one would love one. Any chance of one to test would be very welcome! LOL! Don't be shy!

Fingers & toes crossed!

Chop!