Hi DeepC,
Sorry I did not see this thread before Xmas.
We have had an AirChair for many years. It was the original but SkySki is more popular now by quite a bit. Both are great. My wife is 63 and still rides. Our kids, in their 20's, all enjoy it. My wife rides at about 16 mph GPS and my kids between 19 and 21 mph. You can ride as slow as about 13 mph and be up on the foil. If you are brave and athletic you can do spectacular tricks on them but normally we just tow and launch into simple jumps. That might mean up to six feet in the air so it's still pretty cool. You can do this behind any boat as the wake does not have to be big, although that can help. You need a no stretch rope, not a ski rope. We have started many new riders. Some do really well, but others take a while getting the feel for it. Small movements make life easier. Often the aggressive athlete has more trouble starting to learn than the more passive type.
You can ride in very choppy conditions easily, or if there are many wakes from other boats. It is, by far, our most popular water toy and probably gets used daily in the summer. (and yet I would have to say we are not great at it). They definitely flush the sinuses if you happen to fall the wrong way.
They last forever but take up quite a bit of space in the boat and are heavy. I hop this helps. My family is very happy we invested in ours 14 years ago.