FWIW I just came back from a production of Cats in the best acoustic space in Canada (well, maybe second best now that toronto has the Opera) and I must say that the music was every bit as 'bright' as what I am used to with the M80s. Either you like that sound, or you don't.
That is something I have been saying recently, having attended some live/loud music theater last month. My system gives me the same sound, bright(extra treble), a tad harsh at times, I have always told my wife that was the sound I was striving for and now that I have it, it must be time for a change.