Let's see if I can explain from a technical aspect exactly what is going on. The dilemma with center channels is the various desired end goals can tend to be technically in opposition. The perfect center channel would be:
1) Timbre matched to the right and left fronts for a smooth transition across the front of your system
2) Have all the parts as close as possible to the video screen to keep the vocals appearing to be coming from the appropriate spot.
3) Have identical left to right dispersion patterns.
4) Have very good left to right dispersion patterns
5) Have similar power handling and output to the left and right speakers
6) Have similar spl per watt as the left and right speakers
Using a 3rd speaker identical to the front channel positioned on its side will accomplish every desired goal except 3) and 4). In fact half of 4) will be accomplished.
Using a 3rd speaker identical to the front channel positioned normally will accomplish every goal except 2).
Using a center channel like the VP100 will accomplish every goal except 4). To explain this further the woofer / tweeter / woofer type designs that are so popular for center channels all actually have weak left and right off axis performance. This trade off is popular because it accomplishes 5 out of 6 desired performance goals.
Only using the VP150 will accomplish all six design goals though it will obviously be the most expensive option also. Short of this option you have to choose your trade offs.
