I hear where you are coming from. I had that same Axiom setup for a while, with the QS-8's as surrounds. I felt the same way with the sibilance. Axiom has a distinct sound, some like it others do not. I, like you, did not care for it. The M80's are a very nice, detailed speaker, but they are really forward sounding, so look out once you crank them. Their speakers really need to be used in a treated room for good results.
It did not take me long to upgrade them and I haven't looked back since. if you did not care for them, then you would probably prefer a more laid back to neutral sounding speaker.