Maggie's are renowned for their high definition. Are you sure you need to "mod" them? Someone correct me here, isn't the only thing that can even be modified the crossover? Just playing devil's advocate here; have you listened extensively to a pair? Maggie's also have a rep of sounding great but being demanding of power amps- their impedance is very linear but they are known for wanting plenty of current. Perhaps this (could have) affected what you (may have) heard; Just thinking out loud.
BTW, you might want to contact Magnepan directly; I believe they have a trade up program so you might catch a deal. Good luck with your quest and welcome to the sweet spot.