Well, the link between 'floor XP' and 'prestige XP' is simple enough. If you clear, say, floor 35 while having 35 prestige, both values will be equal. So the XP value for 'prestige X' is equal to the amount of floor XP you'd have gotten had you cleared floor X just then. So (just for clarity), you are saying if I clear floor 20, no matter what my prestige is, the "floor" base xp will be the same as the "Prestige 20" base xp (if I had just done floor 20 with prestige 20)?