Its wheel size is the same as birdy, which also uses long cage rear derailleur.
So the bike has the same ground clearance as birdy bike.
The owner says there are no clearance problem even in conering.
I don't know about its weight.. but it must be pretty light compared to original one.
(I guess 9~10kg range)
Stock Brompton parts are DAMN heavy.
I almost fainted out when I put my brompton rear wheel on the scale.
Geared rear wheel alone weighed roughly two kilograms....
Compare that to new 406-sized Tyrell AM7 wheelset which weighs only 970g for F&R.