I bought my 350 from DK and found them very helpful from start to finish and I've received a bit of discount on parts since buying the bike.
The guy at Oxford classic's is another very friendly and helpful chap. Visited his unit a few months ago and spent 45mins or so chatting about the bikes he had for sale. No hard sell and more than happy to answer any questions.
A few years ago I had dealings with a well known Kawasaki triples dealer from up north. A con man and a complete tool. Avoid at all costs (no it wasn't Rick Brett)