I keep trying to make mage teams work, but it feels like unless a mage team is forced down your throat because of mechanics (physical counters, physical immunity, etc), then mage teams just can't keep up to the damage output of physical. My first clear of the U++ was a full mage team, with multiple stacking magic bonuses, but like I mentioned, it didn't have the dps to finish it fast enough (and all 3 mages had their BSB, so it wasn't like I was undergeared). The physical team cleared it like it was nothing.
Part of the problem is breaks. There's no magical based breaks, so no matter what, you have to bring at a minimum one support physical unit, but usually two for the hardest content. Same thing for soulbreaks. There's endless amounts of soulbreaks that apply stacking break debuffs, and probably 95% of them are physical based, with maybe one or two rare magical SB debuffs.
Another problem is lifesiphon. Being able to slot in lifesiphon (again, physical only) and spam limit breaks is extremely powerful. The closest thing a mage can do (a few of them at least) is cast wrath, but then you're losing out on 5,000-9,000 damage per round from the unit who could be lifesiphoning instead.
I keep reading how mage teams are the wave of the future, but I just don't see it. Unless we get magical alternatives to lifesiphon, and all of the support breakdowns, I don't see how mages can win the dps race in hard content.