I had a pre-order with Wex but cancelled and re-ordered with Sony.co.uk when they brought the price down to £2599 as the quidco with Sony is much higher (saving an extra £150+ hopefully).
Sony have told me that they are expecting a delivery in week 50 (from 10 December). Accordingly, I am ignoring the timing on the Sony.co.uk website (the expected delivery date always seems to be be 21-22 days after you put an RX1 in your basket!).
Quidco - I've never really looked into it, is the cashback thing legit? I'm always quite cynical with things like that for some reason!