tcario,
The whole purpose of the center matching the fronts is to maintain timbre (seamless front sound). Timbre is most noticable in video DVDs/BDs and TV because most most of the dialog comes out of the center speaker. You said it sounds good now, so you might not see much if any change going to a
VocoPro SV-600 3-Way Vocal Speaker (300 Watts, 1x12 in.) In fact it might even sound worse. The ideal match would be a third B-52 for the center.
Good Luck!
Forest Man