Anyways, here's my little doubt and I'll explain it with an example.
Let's say you're playing with Sora and you advance to much in the game. So, perhaps, the Drop Gauge is like a preventive method and when one of the two characters is more advanced than the other, in plot terms, the Drop Gauge depletes faster. This could also help to keep both scenarios on parity.
This idea comes from my perception of BBS. I haven't played the game (yet) but it looks like you can have mini-spoilers when you play an scenario that has similar events to another one. I also read that some cutscenes are repeated in all three scenarios.
Food for thought, well, not actually, but it would be amazing if a Tron-based Moogle makes an appearance in The Grid.
[click link or spoiler tag]
Exodaxe has some questions:
How the drop gauge feature will affect the level up system?
That art looks effing amazing!! And as for the question, like @Rob said, you don't get to control the character past the other one, there's point in the story that you have to switch. I think that my concern is that, what if I wanted to level Sora or Riku then I have to wait to deplete the other one just to level up either of them? >.< Or maybe they will level at the same time? Is there gonna be one level for each of em? or just one for both?