I would concur with Charlie that there ARE kits that are very adequate for surrounds but not for mains.

I have no familiarity with, or even knowledge of, the Outlaw amp that I think you are using. An issue with mixing speaker types / brands is differing impedances. IMHO ability to handle a wide range of impedances is a major but not-often-talked-about quality differentiator between amps. If the outlaw amp has separate power supplies for the different channels, shouldn't be too much of a problem, but if not, watch out ...