My 0.02$. I'd buy the 160.
I dont know if this is possible in your setup or not, but raising the center channel to the position your mains create their 2ch phantom image makes a huge difference in creating a seamless and realistic frount soundstage. (Tweeters aligned). This is especially true for bluray concerts. Game changing.
My previous theater spaces had the VP150 either above or below my 104" screen, and with the right angling up or down, it sounded pretty good, but now with the VP180 beast and a 138" screen, I put it directly behind the screen. Here is a recent picture with my screen wall town down a bit. I have the M60s on small risers to get the tweeters at a better height, and the VP180 up at a height to match those tweeters. Sounds amazing. Just do the same, if at all possible, with the VP160.
Here are some pictures comparing the VP180 size to the VP150. These are from back when I first go the VP180:
And the VP180 next to a pair of M60s:
So what I am saying here is that the VP180 is a beast!
I'd still go with my last statement, and what others said, and go with the VP160 as it is a great design and should be matched super close to your older M60s.
