This killed my M&M game before it got started. All my players said "uh, we have to do how much work to just get started?" and balked. Everyone's married/kids/jobs and doesn't have the time for hours and hours of pre-prep, which is a shame, since M&M looks like it works well once everything is all set up.
I have similar situations with my groups, and one of the best things about M&M is the sheer number of ready-made archetypes available, both in print and in PDF. Just ask your players what kind of hero they want to play and hand them the archetype.
Walt