Not saying that it is a bad speaker cause it's not but for me, the VP150 sounded a bit thin. This is due mostly to the small cabinet. For movies only, I might have been OK with that. The biggest improvement for me was for multichannel concerts where the voice tones are important (it's also important for movies but more forgivable). The vocals just sound more natural from the VP180, almost in par with the M80s. Another big improvement was the bass. A lot of concerts have the bass guitar coming from the center. That was a problem with the VP150, I couldn't almost hear it. The dual 6.5" woofers help the VP180 in this area. The VP180 has a bigger cabinet, more drivers and is overall a better speaker. For me it was worth the extra $$$, for others it might not.
I would have ranked number 1 improvement if you would do 50% HT / 50% music. Since you do mostly HT, I rank it number 2, dual subs being number 1 improvement.
