When I had a Hobie 16, I found that in most conditions (*), backwinding the jib is a really good way to stop the boat, prolonging your tack by forcing you to sail backwards. I have found that you are better served by releasing the jib as soon as it wants to travel around the mast, then trim it on the new tack for power, not as tight as you would have it for close-hauled course at full speed. You may want to easy the main a considerable bit just after you come head-to-wind. I found that about 6’ was the right amount of sheet to let out on the Hobie 16. I believe this is important because of the change in apparent wind as my boat came through head-to-wind. It was going so much slower, although still moving forward, that if your main sheet is full on you couldn’t get down to the new tack and if you did the acceleration was slow because the top of the sail was over trimmed, way stalled!

You noted a difference between 10 and 15. It might be the wave state. Even with our dagger board boat, n6.0, in waves, big waves, we end up sailing backwards sometimes when I pick the wrong time to tack in a set of waves or the jib is cleated on the old tack for second to long. Also, any time attempting to bring the jib to the new tack side to early always, always stop us! Also, with the n6.0, I easy about a foot or so of main sheet after head-to-wind. When the wind is blowing 15, the backed jib may be stopping you much more effectively then when its only blowing 10.

(*) Your wind range with relatively flat water. I recently had two different crew on board for a race. One of them backed the jib once very appropriately during a race. The other tried to back the jib on the first few tack with my response being “Please don’t back the jib.” I think I said please the first couple of times.