Just phoned Unbeatable, they're going to phone Marantz UK and get a release date for the 6300 emailed to me. Impressed with their phone service... very quick.
EDIT: I'd also like to take this opp to apologise for slagging off Leeds Sevenoaks, just been in and it appears they've got some new staff, although a couple of them looked like they hadn't been out of school long, the sales pitch was perfectly balanced just the mix of I'll leave you to it/I'll go out of my way to help you/I want to sell something to you, very professional.
And they've finally sorted out that Plasma, they were showing Lady and the Tramp but it looked stunning.
They also had the spec and price of the 6300 (£549, which seems more realistic, I can't see Unbeatable honouring the £404 price) they seemed to think it was out now and available to order.