Dont want to hi jack the thread, but I would not say mic is "sibilant", the source is.
Mics can be dark, bright whatever, but not sibilant in my opinion.
It just can emphasize \ tame vocalist potential sibilance. Having similar experience with preamps. {harsh vs round smooth sound}
SM7 will do the nice job / as any of another 20 nice mics on the market, depends lots on your taste I think.. - and Id get it anyway. Real workhorse, no matter the style.
Havin couple of suitable mics in mind, but if you can - search around, try to listen to the mics you are interested at your place, and then decide.
Without that you can be pretty dissapointed, or ..surprised.
Just my 5.
Have Luck..