I’ve just been lucky enough to be at Nike Town London for the press launch. I ran in the Next% on the treadmill and they blew me away! So much more responsive than the 4%. I’m collecting my pair tomorrow. Size wise it fits exactly like the original 4% (I had to size up half a size in the 4%...
My Vaporfly 4% Flyknits arrived yesterday and i'm definitely a half size up. The upper is much tighter than the original.
I have a UK 9 in the original vaporfly 4% and pegasus turbo, and a UK10 in the zoom fly. I have gone up to a 9.5 in the flyknits, primarily for the extra width.