Good question Harri. I'm excited to hear what people have to say about this. I just started flat water pumping a couple of weeks before the lockdown but only dock starts with a modified wakesurf board (fairly similar dimensions to a kitefoil board) and that was strapless, so no experience while riding with a wing yet. Will be the first thing I try when we're allowed back on the water.

Hey Gunnar. I'm glad to hear you say you move your feet to trim the board while winging. I do this when I'm downwinding (mainly to apply more front foot pressure when flying down the face of a bump) but thought it was bad technique. Thanks for clearing that up

Been doing a lot of flat water pumping during the lockdown and I can now say without any doubt that for flat water pumping I definitely prefer no straps. Like Gunnar said, straps lead to poor technique, and weirdly, using straps seems to reduce my stability when flat water pumping rather than increase it

HOWEVER, for SUP foiling and wing foiling I still like to use a front foot strap for the following reasons:
 - Extra traction when taking off (especially necessary for me when downwinding or trying to catch super small waves).
 - When losing power from a wave or swell - just to help lift the nose before it touches the water.
 - When cranking turns on a wave!!!!!!!!!!

I'm sure as I get better I'll need them less and less, but I don't think there's anything wrong with using them to learn - as long as you don't get reliant on them.