The issue of a demo and warranty has been discussed before. Here is the link to the thread with Matt's official response. He states that a demo boat is still covered by a warranty.
viewtopic.php?f=11&t=47840&p=211618&hilit=demo+warranty#p211618If the word "demo" was not obvious, it probably would not bother me at all. As far as stating a discount, it's in Hobie's best interest if a negotiated purchase price is not publicly discussed as that keeps the pricing on a level playing field for the dealers.
It's up to the dealer to decide if they will give you a discount (especially for purchasing more than one) and most want to discuss that in person when you are in their shop. I can only speak from my experience and live in the U.S.. Not sure where you are located.
My Hobie dealer is very good to me and I've purchase several Hobies from him. Sorry yours did not work out as there was a mis-communication during the purchase process.
Best of luck with your PAs. You will love fishing from them!