Don't respond if you are a beginner/intermediate!

[consumer]

55L here and weigh 85 kg

I downsized from an 85L , and my conclusion is that the trade off in low end for maneuverability is too great to justify going below ~70-80L at my weight. However, my 55L is pretty heavy and almost weighs the same as my 85L, which is light for it's size. My conclusion is that weight makes the biggest difference for maneuverability, wave riding, and pumping.

If I'd do it all over again I'd say make sure you prioritize weight and don't bother pushing volume as low as possible. My opinion is you don't get much in return for loss in low end and safety (floatation in case the wind dies).

[bragnouff]

You might find some different answers on different forums where perspective isn't tainted by kiting experience.
Sure there is some appeal in smaller boards, but a big part of the appeal of winging is also about getting many more days on the water in potentially gusty holey winds, and being able to slog 200m carefree before getting into the wind line is part of that game. For that, I'm happy to have a reasonably sized board (+5L) that is light and compact. I also like riding with just enough power and max efficiency, which (for me) is part of the magic of foiling. Having to use a larger wing just to get on the board defeats that purpose, and obviously it is not always possible if wind is just not strong enough (and even more so if you're a large rider).
As kiters (and kitefoilers) we already know what it is to ride small boards, what it is to jump, and we also have the options to use kite gear in some conditions where it makes perfect sense to do so. For the good windy days when we decide to take the wing foiling option (usually a decision based on the waves factor), having a "big" board isn't actually causing much of a loss in terms of fun factor compared to something significantly smaller. I see being on the wrong size of foil a much bigger annoyance than the board size itself.

Now if someone was only wingfoiling (no kiting or windsurfing), and wanted to cover all conditions and push the boundaries of jumping, then it's possibly quite a different state of mind.

[Jan:)]

I use my 45L board only rarely.
That is, if I have an easy launch, strong and reliable wind and its not too cold.
Unfortunately that adds up to about 3% of my days

Otherwise I take my 80L board.
There is really only a minor difference for me.

But weight is the key point there.
My 80l is 4.6kg the 45l is about 3.7kg.
So there is not that much difference once you factor in the foil and everything.

If you come from a much heavier board, you likely notice more of an advantage.

[airsail]

I’m 80 kg and gone with a 74ltr 5’3 x 22. It’s slightly longer than my old 4’10 x78 but seems to get going better with the extra length. I won’t go smaller as I know I can always get back even if the wind drops on the 74 ltr. It’s just 5kgs on the scales so not too much swing weight, ineggra/glass construction, no carbon.