Well, I will offer this;
I have never heard the VP100 - so I cannot comment on it.
I have never heard the Qs4s - so I cannot comment on them.
I own the VP150 and think is is terrific. Does it's job in a solid and competent manner.
I own a set of the Qs8s. They have made more of an improvement in my HT than just about anything that I can think of. Sure, the M60s get more work, just because I listen to alot of music, and I love 'em. But...
So far, in living with these Axioms for a couple of months, and comparing all of my pieces with everything else that I have used over the years, and trying to remember everything that I listened to while shopping for other speakers, I might just have to say that the Qs8s are one of those "Best in Class" kind of products.
All of the Axioms that I own are wonderful.
But the Qs8s are off the charts as far as value, completly crushing anything else that I listened to for hundreds more, and for the difference they have made in MY HT setup.
YMMV!!!
I'm sure the VP100 is more than good enough.
(And Heck, for all I know the Qs4's might be wonderful too!)
But the 8s are just insane!
And, to blather on even more, they are easily the most forgiving surround speakers, as far as placement goes, that I have ever had in my system.
