You seem pretty sold on the B6 so will it matter what I think? In the end this is your system so you do what makes you happy.
Yes I did mean three "center" speakers to make an LCR setup. That where you use the same speaker all the way across the front. You connect a "center" speaker just like any other speaker with some speaker wire. There's nothing magical about a center speaker it's just a speaker with an extra mid-bass driver. You normally get a slight bump in efficiency due to the extra driver and the benefit of the same speaker all the way across the front.
No I am sold on any speakers yet. If I can stretch my budget and get KEF Q500/Q700, do you think they are better fit for my room size? my room is big but I don't sit very far. I can get Q700 just $100 more than Q500. But will Q700 be overkill to me?