Do you mean the F4 board has a lot of tail rocker?
Interesting discussion. I've always thought the main reason why guys are able to lean their boards to windward so much is because of small foils and narrow boards..
Peculiar. I could not tell if the nose is high or low form the picture, but looking at the F4 board profile, it is clear that the tracks are indeed angled that the nose would be higher. In the right image, you've got the board angled more, so the apparent wind would push the nose down more. To compensate, moving the back foot back into a wider stance makes sense.
What would that have to do with the angle change, though? Here's a theory: when dropping the rail to re-direct the lift so that you can go faster, the rail gets closer to the water. Touching chop or waves with the forward section of the rail could cause problems. increasing the fuselage angle to raise the board nose would reduce this problems. There's been plenty of posts about shimming the mast plate to also increase the angle; IIRC, one argument was that this also makes touch down recovery easier. The F4 guys seem to be into racing and going fast, so maybe there's something to this theory.
Faster foils (or even just riding faster) like more mast rake, which usually means more tail rocker. going faster means the drag of the whole system (mast, fuse, etc) is increased and there is a forward pitching moment. So having nose up to start means it's more balanced at speed. I personally also find it easier to get going. I like about 4deg+ rake on my mikeslab foils.
As for stance width. I think you'll find that riding more aggressively encourages a wider stance. narrow is better for pumping. But that's not aggressive riding.
My guess is that as foils are improving and riders are adapting, we'll start seeing more boards shimmed or rockered nose-up.
I think this picture explains well how it is.
And after discovering this, I have been googling a lot about rake/rocker. And I read many places that guys on fast foils have quite a lot of rake/rocker, to have 3-5 degree angle difference between the deck and the fuselage.
