Classic example of this is the fact that (so far, I believe) that no Spitfires have come along to an F16 event as they are rated slower and so feel that there is no point. It's only 1% between F16 2up and Spitfire, however it is about 6% between F16 1up and Spitfire.
Simon, I ignored this comment until I had the usual Saturday bottle of wine

The Spitfires have a "One design" circuit, with 25 boats at their Nationals. Apart from JP, as far as I know, no other F16s have ever challenged the top Spitfire sailors at open events.
I hope that some day the Spitfires will enhance the F16 fleet, but at the moment there is no contest in the UK or France.