That's an interesting idea with the hearts. It'd be like compressing health into a smaller container! I like it, but as StarWolf said, it'd cause some issues. The current overlay animation works pretty well, so we will just keep it as is. If you remember in Ocarina of Time, when you get the upgrade to your life the heart gfx have a bright outline to them. It's the same idea but for the whole heart, and it's very easy to differentiate between the two.
lexluthermiester, that mock-up of the HUD looks great! I've never liked the yellow hue of the HUD and have tried doing experiments with it in the past, but I never thought to make it all black! Some elements would have to be re-worked, though, like the white outline of items. That doesn't look quite right. Overall, though, I agree that the black does look better. If I can redraw items/inventory elements in such a way that they look good against a black background, then it may happen. Thanks for the idea!