Exactly the same reservations. I did speak with these guys on the phone a few weeks back. IMHO if it's a high production mass produced boat (e.g. Grady, Trophy, Striper etc...) that sell widely in the US they can likely get you one cheap. They are buying bank repo units off auction. Your risk is that if they can't find you anything, they take a $250 cut. Plus, you lose any exchange on the US dollar -- which doesn't sound like much, but count on it being another $1-200 after the bank takes their pound of flesh.
It would be great if they'd agree to work with a Canadian Bank or Escrow service. Put the money "In Trust", they find the boat and if it meets your conditions, money is then released. The way they have it set up, they have too much control over your money.
One place in the US I did have some recent success is with POP Yachts out of FLA. They were able to find me the perfect boat out of Everett WA and really wanted to work hard for the business. It's worth visiting their website and letting them know what you are looking for -- doesn't cost anything until you want to make an offer.