It's usually best to use the same speaker or fronts & center, but 2 way/ 3 way doesn't really matter. Also, Center channel speaker is for Dialog, not full range sound. Voices don't usually go down into the bass region, nor does it soar up to 18 Hz either. There is still one disadvantage to a 3 way vs. 2 way. You have 2 crossover points instead of one. Depending on the sophistication of the cross over networks, it could change things.