Has anyone fitted one of these? Are thay SVA friendly?

Not sure about sva freindly YET but construction and use only requires no plate to be adequately lit and plainly visisble from rear. There are no angles of visibilty etc but i'm not sure whether it needs an E mark.

Yep, number plate must be well lit, light must be white and as far as I can see there is no 'E' mark required as there is no specified light pattern or intensity to adhere to.

There should be no reason why you can't use LED's

Ta!