From a physics standpoint, a 6.5" can be engineered to sound better than a 6x9 ever can.
really? I never knew a 6.5" can outperform a 6x9". When i was reading the first few posts on this thread i was wondering why would one replace a 6x9 with a 6 or 6.5. the bigger the dome the more power and bass you get right?