Center channel or 3rd matching speaker ????

Looking at ATC - Would you go three 150's across the front OR two 150's and use their big c6 center channel ( which is two asl 50's put together)-I have read that the matching speaker is better for music and the center is better for movie dialouge??? also any thoughts between going with the 100 active VS. the 150 active- my room is 16x28- thanks K-