I have owned two jetski's a yam 1200XLT LTD 2-stroke, and a yam FX140 4-stroke and I have to say they are great fun. Both ski's are designed to carry three people, however, two realistically, and if you want out and out fun and exhiliration ideally one up. With two people on board it is difficult to stand up, but one up it is sheer fun but hard work in rough conditions. I have ventured out of Porthmadog in a force 5.
I went on the 2006 ribnet raid from Pwllheli North Wales and was the only ski that joined the flotilla and I was two up, and in moderate conditions I nailed almost all ribs bar one maybe two large ribs. Thanks to Top Banana he carried extra fuel, my wife and one of my two lads on his rib, I topped my fuel up at Barmouth but I am sure I would have completed the 75 mile round trip on a full tank on my 4-stroke. Just over 1Nm per Ltr. any distance longer than this, and someone would have to carry fuel for me.
Problem with ski's when you have a family is you cannot get everyone on board, and you have to keep returning to the beach to give rides. Ribs are far better for families, you can load up and go for the day.
I always carried a handheld GPS and VHF radio, problem being you do not get the 25 watt coverage with a handheld VHF. On a ski you always get soaked unless you are a wuss, whereas on a rib you more often than not stay relatively dry unless it P***** down.
One thing I have noticed with ribs compared to ski's is how hard the hull slams onto the sea in choppy conditions, not half as bad on a ski.
Still after all that, ski has been sold, and looking forward to owning my own rib. Probably a 5.8 Vipermax, I like the solid well built hull.