My idea was to try to model the builds as how they are reflected in the comics. I wanted to see how the game would play out with a mega villain vs a group of heroes. I admit that play balance is a bit of a problem when you have heavy hitters going against street level heroes, but for me it works.
I did some builds for the Liberty Legion and various Super Axis types and kept them all around 75pts, except for the sidekicks, and the game was well balanced, but seemed a little too flat for me.
That being said, it shouldn't be too difficult to use my builds a base and adjust them up or down to 75pts. to more in line with the rules.
Hope this answers your questions.
Looking forward to seeing your X-Men and Invincibles builds.
Troll