How important is the Centre Speaker ?

Not important at all to me. I've tried many different center channel speakers, and found no center channel to be the best option. I prefer the 'phantom' center channel. I believe if your front speakers image properly, the center speaker only messes things up. That's my $.02.

Kkm, you may be doing something wrong. You have to program your processor to 'NO Center', so it knows to send the center information to FR & FL speakers. Otherwise the center information will still be going to the center channel speaker, whether you have one there or not.