i had a vp-150 for like um.... 6 or so years... and i though it was pretty good.... whenever i listened to music, i would always listen in stereo... never really used the processing... now today, i do not use stereo much anymore, due to the vp-180 being able to keep up with my m-60s.
the 180 blends perfectly, where as the 150 you could tell that there was a difference between the center and the L/R speaker. if you look in the vp-180 thread in the home theater section, i posted some pictures of the difference between the 150 and 180. I would say the 180 is about 4 times as deep as the 150..
depending on your finances, if 287$ isn't a big deal to you, i would say go for it in a heart beat.
my sound level is the same, but the 180 has 500W going to it now, where my 150 had 250W, due to the lower resistance of the 180.... the 180 does fill the room more so than then 150 really ever did....
i hope this helps, if you have any other questions i'll be around
