I think my Crosslights must have been pretty close to the claimed weight, a few grams here or there and that was with the (standard) rim tapes fitted. Never tried the skewers though.
Whilst researching, I read that 25mm was unofficially ok, I think some magazine had asked Kinesis.
I can’t say that I expect any corners to be cut for £250; a Stans Crest/Hope wheel set weighs and costs slighty more, but that’s a wider rim with heavier hubs from ‘better’ brands.