I have purchased stuff from both and find KL to have a much better inventory and cheaper delivery prices. On 2 occasions I have received a product with a problem they replaced it no questions, in fact I received one before I had a chance to send the faulty one back. KK don't even stock oak...
I had a faulty Mark4 regulator. I called them, they sent me a post paid sticker by Email and a replacement regulator arrived before I had a chance to mail the faulty one back. Great service, never had a problem with KL.