I had the QS8v2 for 11 years in my 4200 cu ft room. They were each installed 11 feet away from the MLP and slightly forward. They were puny. I upgraded to the QS10 and I am very happy. I have them crossed over at 40Hz. I can't believe how much I was missing with the QS8.
I've never heard the SVS. Based on specs, the QS10 will play lower and louder likely because it has the 6.5" high power driver. It's likely also more dispersive given the the quadpolar design.
I also have the 800, 160, M100, M3, M5 all v4 and love them all. The HP driver is terrific and I can't say enough about the tweeter. With all due respect to Axiom, v2 was crap compared to what I hear out of the v4. Read my product reviews; v4 is magic. I can't get enough of it.
You might want to consider the trade-in and member loyalty programs when it comes to deciding. I'll be upgrading to QS14s when available.
