No, a vertical speaker needs to be mounted vertically. If there is no way to use a vertical center, then a speaker designed for horizontal placement will yield better results than a vertical on its side.

I'm not even talking about sub range, the VP100 starts rolling off at 95 Hz, were as the VP150 can reach a bit lower to 85 Hz. That's still within the range of male voices.

Pioneer PDP-5020FD, Marantz SR6011
Axiom M5HP, VP160HP, QS8
Sony PS4, surround backs