I recently upgraded my mains to KEF Q5's. It was such an improvement I am planning on upgrading my centre speaker as well. ( I have older KEF 60S as the surrounds). I was going to get a KEF Q9c, but my dealer has an odd (single) Q3 that he will sell for less than the Q9c. The Q3 is easier for me to place in my setup (as it would fit nicely under my screen and working out how to install the centre is a nuisance for me). So the question is, can a KEFq3 tower operate as a centre speaker ? Looking at the specs of the two speakers it's only the bass extension figure that looks different so I figure I can always bung the port if you are not suppose to have too much bass from the centre. But I don't know if there is any other difference between a centre speaker and a main type.
That would be a great center channel. I have seen people use towers before with success. Usually it is a space issue that forces the smaller center channel. Will your dealer allow you to take them home and compare the two?
There is no difference between a good centre speaker and a good main speaker. Kef speakers are neutral and will not give you bass that is not there on that channel in the source. If you listen to DTS movies and/or DVD-audio, then a full-range centre speaker could be just the thing.