I did what you're doing. I always like having a tank, a healer, and a DPS role leveled similarly so I can use whichever I want at any given time. I typically do MSQ with one class, sidequests with a second class, and then daily roulettes with a third, but I frequently find that sidequest class ends up doing quite a bit of MSQ, too, since my MSQ class gets well ahead of the MSQ itself in level.