I had a look at it last Sunday.
It was lighter than my Brompton - but mine is a six speed and had the bike cuffs on the saddle rails at the time, and the electric one was single or two speed, and it didn't have a battery on.
But, things that impressed me....
When it was folded, without a battery, if you pick it up the balance doesn't seem to be affected - it doesn't try and lean in one direction.
I picked up the battery, that didn't seem very heavy - 2.6kg is what I've read. It clips onto an extended luggage mount with a flap to cover the connections (as they face up)
It was in the Brompton shop in Covent Garden, they said that if I came back after the BWC then I could take it out and try it.
It seems a fairly hefty premium over a regular Brompton, but next spring after struggling through headwinds after long days at work, well I might be very tempted.