I had the ML 15i and didn't find it bright but I tend to favor speakers some find brighter for whatever reason. Had Focals if that tells you something and have a variety of others that most would not call dark or warm.
Although they were very articulate and voices semed natural with good control of sibilance and very suitable for movies, they couldn't convey space/spatial effects well in soundtracks and sounded a bit unnatural and perhaps fatiguing with music particularly instruments for me.
I blamed this not on the tweeter but the Alum woofer that for some reason I do not seem to like. I tried alot of speakers with Alum drivers, some better for my tastes than others but all sold or returned, regardless of the great discounts I received.
I would say if they are bothering you, either you can sell them or if returnable, then do so. Some well liked speakers by most do not work for all.
As for myself, I seem to like paper/treated and/or polypropylene woofers better regardless if the tweeter it soft/metal/AMT, etc. Metal infused drivers seem to much in certain ways for me. Even if it is made to sound refined, it still seems off for me. Exciting yes, overall listenable...not so much, but that's me.