Be careful comparing and deducting too much from polars
In my experience, they might give you an "idea" how the performance has been, but they will also have a huge error margin.
Must say I dont like em myself, eventhough they are pretty ha haa
Because, you never have stable wind exactly the same direction, and even quite small windshifts, will make the polar way to good than it really is in terms of angles and speed - you seem to be able to go crazy upwind and downwind at huge speed, which in real life is not the case and blurred by an unknown factor of windshifts.
Even IF you have consistent wind, it will often change direction slightly, when you ride closer to shore, compared to a bit more out, so here is also an error.
One has to look closely at the exact tacks and measure the average VMG on these (both tacks right after each other), in order to get any really useful information.
Also, take Gunnars examples with the racefoil and Go foil - it looks like the Go foil can not go fast nor upwind at all
And this is not true - to some extent of course yes this difference exists, but in the first scenario it is powered maybe with a racekite and heeling upwind pushing hard, in the second scenario it is extremely lightly powered with a tube kite, and not cranking upwind but having fun in the waves.
If you turned the kites and goals around, you would see a very different picture