Love the the mod, much more enjoyable than elytra. It draining hunger on use is a good mechanic to tie it to for balance reasons. Personally using it myself, hunger becomes a lot less hard to manage later on when you acquire wings, so it feels less like an inconvenience using a powerful endgame item. Possible suggestion for an optional config, drain experience slowly when using it? That way it feels like a luxury to use it such as flying off cliffs or avoiding death, but not at a too fast rate that it becomes annoying to get exp. I suppose its not impossible to an option to change how fast/slow it decays like you did with hunger in the config. There's no real use of levels in minecraft except enchanting, so it would give the incentive to keep collecting exp above lvl 30 to stockpile a lot of time for using your wings, giving itself its own resource to manage at a slight detriment of the player.

If you don't like the scope of the idea, or it isn't worth time implementing it, then thanks for reading either way!