I don't know anything about Catalina and you say you've looked at HS. Have you looked at Marquis, Sundance, or Jacuzzi? They also have intermediate lines for less.
If you're completely sold on the Catalina I would make sure you get that warranty in writing. How long has the dealer been in business? He's saying he'll give you a full warranty but what happens if the dealership changes hands, sells or closes? Have you wet tested the hot-tub? Personally, I wouldn't buy any brand without wet testing.
My advise is to look at some of the other brands. Good luck.