Well Brian to each his own, but just offhand, i would experiment a bit more with the 'width' at which the speakers are placed.
I had my M60s placed about 5 feet apart and hence the Vp150 in the middle (probably about 2 feet from either M60, same as you).
Once i got my big screen tv, i had no choice but to push the M60s further apart. When i did that, i noticed the soundstage improved dramatically.
I played around with 'toeing' in the speakers as well, and again, there were fairly large differences in the cohesion of the soundstage if i toed too much or none at all.
I certainly have found the Axioms front speakers to be a bit picky in their placement but the biggest and best change still came from simply moving the mains further apart and causing more separation from the VP150.
An alternative that has been suggested as of late is to use an M2 or an M22 as a centre channel instead of the VP150.
Personally though i've found the clarity of the vp150 to be a bit less than the M60s but to me this is perfectly fine since i've found the M60s to be bright enough on their own and i expect the centre channel to be an enhancement to the 2 main speakers and not a stand alone performer. In my opinion, the centre channel should help to carry dialogue/vocals across the front and to fill in the soundstage in the centre. For HT this is sometimes also accomplished by not using a centre channel and just turning up the tv volume, although this obviously creates a crappier quality sound.
