Huw,

doing my best to be independent, and noting we are on an F16 forum(!)... Regarding Spitfire for use with kids - I was successful at a club level with a (small/light) 13-16yo crew. If your kids are smaller, they'll probably not have the power to control the kite, although I am tempted to say that if they're inclined to go out in stronger winds, I suspect they will also cope with the sheet loads. A comment specific to the Spitfire - you can double up the purchase on the mast rotation and downhaul, class-legally and easily. You could also add secondary blocks for the spinni, legal for long-distance races. All that makes it feasible for younger crew.

Spitfire solo? I'm 80kg dripping wet and decided it wasn't for me after trying it. I'm also not inclined to get fit for sailing (I'd rather go sailing), so I like lighter sheet loads as well. I think it would be difficult to right solo - I never managed it unless the crew was contributing too.

Your requirements sound suited to F16 - but then you might want to think about the size of the fleet, local activity, and resale values, in combination with how often you will sail solo / 2-up. However, I love the F16 concept.

As you are in the UK, think about Shadow. You cannot fit a jib, or second trapeze, but the spinni would be easily managed by a young crew. So, I'd suggest it is suited you solo, whether racing or pleasure, also to fast pleasure rides for you with a youngster, but not realistic for full-on racing in that configuration.

And being a small, light boat, it feels fast. Mine feels even more 'responsive' than the Spitti, and as fast, but I am yet to sail against my fellow club sailors who are still hibernating, so I am suspending final judgement.

Rather than put links here, I suggest you search for Shadow sailing forum, or British Spitfire Class Association, and seek input there too.

At the end of the day, a test sail or two may help you to decide.