The reason I want to do an all muties campaign some day is because I want to play with all the classic mutie tropes of being outsiders. Now, I can do that in a no holds barred, any type of character you want game. But I've always been bothered by the disconnect caused by the general public hating mutants, but loving super heroes in general. How does the average punter know the difference between Cyclops and Spiderman? Why would they even draw a distinction?
I would have tech powers, but limited to real world tech (more or less.) And I would insist PCs have at least one innate, mutant power. Mutant powers wouldn't be limited, except to the AP cap that we selected for the campaign. (Which, off the top of my head, I'd put at 70AP.) This would make mutants significantly better in a fight than normies. It also gives mutants access to things like psi, teleport, and phasing that the normies just do not get.
This in turn means that when the Siblinghood of Naughty Muties does crime the only ones who can stop them are the PCs.