Jappy,

Typically there is not much LFE with rock music. Jazz, Classical instrumental, Rap, Hip/Hop etc., do need greater support. Given the price of EP350, I would look at other good offerings as well such as SVS, HSU, Elemental Designs although the looks may not be that great compared to the Axiom. This would still leave you with upgrading to VP 150 since I personally find vocals through the center channel to be the weakest link in my listening experience. Also I would just stay with the QS4s as you wont see a bigger benefit with the surround experience than the previous options.