I'm not familiar with your JBLs. I have the Axiom speaker combo you're looking at, though. The M60s throw a wide and tall soundstage in my family room - very open and airy. Midrange is excellent. My M60s absolutely destroy my Monitor Audio Bronze 2s in every way (granted $800 towers vs. $400 bookshelves ).

If you only need a center and surrounds maybe get those first, see how they match up with your JBLs. If they blend well enough - good deal. If not, order the M60s and you'll still get the 5% package discount.

Good luck.