Hi Mulver,
You've done some good research and yes, getting an Ozone Uno is a great idea. However, here are a few things to consider:
-Don't think of the Uno as a trainer kiter, it's actually a kite that is in every aspect the same as a normal kite, just smaller and with less struts. For your 8 y/o, a 4m Uno would actually be a great size to do anything from body dragging to water starts and riding in the right wind conditions (say 15 to 20 knots). Just to give you an idea, I recently taught a friend of mine to do anything from body dragging to water start and ride upwind on a
3m kite, she's 60 kg and winds were 25 to 30 knots (see pic below). So for your eldest kid who is half the weight, you would need a lot less wind to achieve the same results with a 4m kite.
-For you and your wife, a 4m Uno will have a limited use...once you get to the stage of wanting to get up and going on the board, that kite will be
too small.
-I strongly recommend you get the Ozone bar to go along with the Uno, it has a great safety system and it's a bar that you can use with larger kites that you would buy further down the track.
-Ideally you'd be getting both sizes of the Uno, so if the wind blows at 20 knots or more you can put the kids on the 2.5m instead of the 4m. The biggest issue with the 2.5m Uno is you will need a bare minimum of a steady 15 knots breeze to keep it in the air. Ideally it would be 18 knots +. The 4m needs a minimum of 12 knots to start flying easily. I'm not familiar with SA wind conditions, but if most days are light/moderate winds, you may not get much use out of a 2.5m Uno.
-A 4m Uno on normal length lines (24m) for your kids is a big kite with a massive wind window and definitely not in the ''trainer'' kite category anymore. I've seen parents trying to teach their very young ones on Uno's in 20-25 knots, some very scary stuff! It's the equivalent of a 90 kg adult self-learning to fly on a beach with a 12m kite in strong winds, just not safe! Remember that just because you yourself can fly a 4m kite safely on the beach doesn't mean you can necessarily teach your kids to do the same thing safely.
-As you are getting a ''real'' kite, you will
need harnesses for everyone. It might be a challenge to find the right size harnesses for your kids and they might outgrow them quickly. If you can't find the right harnesses, it's pointless to get your kids to fly. Since your kids are so young and so light, it might actually be a better idea to get them a 1m foil (2 line) kite, which doesn't require a harness and fly's well in a light breeze. It would be a much safer option to begin with and these kites are very cheap. It might take a few more years before your kids develop enough interest, physical strength, stamina and become competent swimmers who are comfortable enough being in the ocean to start putting them on a board. I have a friend who is a keen kiter and a father of 2 girls (5 and 8 as well) and he has not even thought about putting a real kite in their hands just yet, he's gonna wait a couple more years if they have interest...just toy kites and a few minutes of small foil trainer at a time is all they can handle for now.
-If you buy a Uno and try to self-learn with your wife and kids, there is a good chance you will develop some bad habits and potentially endanger yourself, your family or other people around.
Do yourself and your family a big favor and book at least a first 2-3 hour lesson to learn the basics of wind, wind window, wind direction and strength, location analysis, kite setup, launching and landing, safety systems, kite control, water relaunch, etc.
THEN, after this initial lesson you will be much safer, knowledgeable and have the correct skills to continue flying on your own and teach the family.
-If you intend to do a lot of beach flying on the Uno with the family I strongly recommend replacing the normal 24m lines with some
short lines (5 to 10m lines), this will make the wind window a lot smaller, which means a lot safer and easier to manage for the kids. Short lines are also a lot safer for everyone else around and you are much less likely to damage the gear by crashing the kite in the bush or sharp grass for example...You can buy a set of Ozone 5m line extensions and replace your normal lines with those in a few minutes.
-Remember that learning the safe and correct techniques with a competent instructor from the start is much easier than trying to break your bad habits later down the track... In the process of trying to self-learn everything from scratch you will most likely put yourself, your family and other beach users/kiters at risk, even with a 4m kite.
-Keep in mind we're getting towards the end of the season and there is only a limited amount of safe wind days left. Once winter fronts start to hit, it will be much more dangerous to fly kites, especially as beginners.
Stay safe,
Christian
it's great. 
