The treasure paradigm from 3E, though I've supported it because of "fairness" I honestly don't like. I like back in the day having a golf bag of different magic swords, each having a cool name and purpose, like the flametongue, frostbrand, and dancing sword.
I like the idea of a treasure dungeon, but some of your ideas I'm not sure about. Abandoning the dungeon and thus having it disappear forever would be aggravating, unless the players really understand the consequence for running off to town because they want ale and whores.
I like getting XP from treasure, but I'm not sure how making it the single avenue for advancement will work. It might create squabbles about who gets what items.