I would not suggest a change in either until I knew more about the application.
If the OP is using the system 100% for movies and/or gaming, the current speakers are fine and I would concentrate on video image quality and size, room treatments, subwoofers, Dirac or REW, and amps.
If the system is primarily 2.1 channel music, then it makes sense to upgrade the main L-R speakers and better integrate a sub.