"I could never put my finger on it until I had a demo with the Sophia 3, thiel 3.7 and B&W 802D all in the same room for an A/B/C demo. The Thiels had the worst case of this issue (diffused vocals) but the best lateral dispersion. The wilsons sat right in the middle of focus and dispersion and the B&W had a laser focused midrange."
I can understand your overall experience. The issue with the Thiels are the easiest to explain because they're time and phase correct. They don't give a back tilt adjustment like Vandersteen does, so the positioning has to be perfect. Your head has to be just in the right spot or you'll loose everything. It only takes a couple of inches.
I guess when I read the OP's story that the B&W's are outperforming the Wilsons, I tend to panic. I had the 804's and several other pairs. All I can say is that I've owned many different brands, but I consider myself a victim when it comes to B&W.
I believe shadorne has some good advice. We know the speakers are wired in phase so the next logical step is placement. Definitely try moving them closer together. If all of your components are well matched and of good quality, your system should have no problem imaging beyond the outside edge of the speakers. Actually, I have a pair of Wilsons myself in a 2nd system I put together. They're not as nice as the OP's, but the imaging still goes way beyond the outside edge of the speaker.