I bought a kawasaki 650 brand new in 1989 and had an absolute blast on it. A couple years after that I got a new 750 soon after they came out. That was 10 times more fun and rode a lot nicer. I still have them both but have not ridden them for a couple of years, never enough time to make it to the lake. I can not stand the sit down modern day versions, they are way to boring. You can do lots of tricks with a stand up and they are more of a challenge to ride, it takes a little more strength to ride than a sit down. If you never have rode one before, try starting on your knees like you do with a wakeboard, do that for a while until you get the feel for it, then once you get a little speed up, stand up and ride. Practice and soon you will be doing 180 degree power turns, corkscrew power dives and nose diving like a pro. I am not a pro, but I sure had a blast on them for about ten years, loved it more than any other water sport. But now I have not enough time to enjoy them, but I keep them with the intention of getting them out some day again. I better stop before I write a book, lots of good memories..........................
As far as pros and cons in the machines, I only had kawasaki and all I ever did was put fuel and oil in it, pretty much bullet proof. I even drowned both of them several times and got them going again real easily. They have a cable for this, but cant remember what its called, been to long and I am too old to remember. My neighbor had a 550 for a while, but traded for a 650. I say get a 750sxi ( i think it was sxi ) they were a sweeeet machine. I was going to get one the last year they made them, but never did.