So, the mission rewards outline XP per player, but in a five-player game, that would mean each hero would have that XP point available for them to spend. Meaning, if I wanted a 4xp upgrade for one hero, by the time I had those 4xp for one hero, another player would also potentially have 4xp for their hero as well.
In a 2 player game, based on the mission wording, each hero basically receives exactly half of what they'd be getting if they were controlled by 2 different people. I really think this makes the game much harder for the rebels in a 2 player campaign, since it takes twice as long to upgrade as it would if there were more people involved.
I'm thinking this is the only reason we are both just getting destroyed by the imperials in nearly every mission. We're going to try a campaign with this 'house rule' (each HERO receives 1xp) and see if it's any more balanced for us...
If I'm missing something here, let me know.