I would shy away from them at this point. I don't see interest rates falling substantially in the near-future, meaning in your shoes, I'd be deciding amongst a 10, 15, 20, 30, and 40 year fixed rate mortgage (and maybe considering a 5/1, 7/1 adjustable if you really need to squeak out a little lower payment now).
Advantages of the 15 over the 30 is you pay about 1/2 % less interest, but your monthly minimum payment is much higher. For that reason, I'd be inclined to look out towards a 30 year (normal) mortgage and just pay extra in times when the business is throwing off a lot of cash.
The short-term mortgage seems like a hell of a lot of work and risk (of requalifying essentially continuously) and that site is utterly unconvincing to me (and I'm on the risk-seeking side of the spectrum of people generally).