Ok, I know tons about jet boats.
Our first jet boat was a 1999 Yamaha Exciter (270 HP, twin jets) AWESOME BOAT. This boat is so fun, tons of power, can pull jet skiiers and anything else you ever wanted. We bought this boat after doing tons of researching and testing all sorts of boats.
We narrowed it down to SeaDoo or Yamaha. Upon further research and reading forums the Yamaha is all around more powerful/faster/and funner boat. The seadoo's only have one jet. Also the yamaha's dual jets are more accurate while driving because the seadoo only has one jet and lets say it spins clockwise, that means that the boat is always wanting to pull a little bit to the side. The yamaha has one jet running clockwise, and one jet running counterclockwise, to even it out and keep it straighter.
My neighbor has a seadoo (not sure which one it is) and we go boating with him all the time and our Yamaha is faster and more reliable (his seadoo seems to always be going into the shop to be fixing minor problems). Also with the dual jets it's a little safe, incase one jet dies, you always have the second one to get you back to the land.
We recently upgraded to the
Yamaha LS 2000. This is the exact same boat as our exciter, except it has two extra seats. It's not as fun to drive, or as nimble as the exciter, but it's still a great ride and was worth it to us.
If you want the fastest most powerful jet boat out right now, You want
the XR1800. I test rode this thing, and it flies. It's about the same size as the exciter, but more powerful and different design without an open bow.
Oh and my cousins have a little Sugarsands jet boat piece of crap, i'd rather swim then ride in that boat. When you go top end in it (which is only like 40mph) the thing rattles and feels like it's gonna fall apart.