I also auditioned the RS6's when I was searching for a speaker. While I think they are decent for the money, the SongTower's are better in every way IMO. They have better midrange clarity, more punchy tight bass (as opposed to the RS6's somewhat bloated bass), more realistic high frequencies and timbre, etc. The difference would be like looking out a smudged window at a beautiful sunset. Sure, it still looks nice, but with the SongTower's there is no pane of glass, so you see (or rather hear in this case) what you're suppose to.
Hope that helps.