Should I get floor standing fronts?

[Blacknd]

Hey guys,

Just to start off I'm pretty new to better end equiptment and setting up a good audio/video system. I'm building a system and what I have so far is.

Denon AVR-2807
X-box 360 w/HD-DVD Player (will upgrade to a dedicated dvd when the bluray hd-dvd war ends)
Sony DVP-CX995V 400 disc dvd player for the collection
SVS 20-39 PC-Plus sub
SVS SBS-01 5.0 surround speakers
Bluejeans cables
Logitech Harmony 880 Remote

I am soon going to 7.1 but I also listen to music as well, the system is more for home theater than music but I want to eat the cake too. My question is should I get tower speakers to replace the 2 fronts or get 2 more SBS-01 surround speakers? I want to get towers for my cd 2.0 listening but the sound that I have now is perfect for my ears for watching movies and I dont want to ruin the speaker relationship to each other by adding in fronts that wont balance well in relative sound to each other. Am I overthinking it? I have about 1200 to 2000 to spend on the fronts. Thanks for the help in advance. BTW I was looking at Axiom Millenia M80 v2 but they are 4 ohms vs my current 8 ohm setup, is it possible to add a 4 ohm speaker to the 8 ohm setup? And how good are the speakers?

Almost forgot I'm stationed in japan for another year so I wont be able to go listen first