singer A + mic B = sibilance
Singer B + mic B = no sibilance
Singer A + mic A = no sibilance
Singer B + mic A = sibilance
however, it is possible that
Singer A + mic C = mic B>sibilance>mic A
but at the same time, possibly
Singer B + mic C = mic B>sibilance>mic A
or not.
my point is its more about matching a mic with a singer rather than some mics having sibilance and others not. each singers sibilance is at a different frequency. some mics might have a boost at that frequency making it worse and some might not. but its specific to that singer. I guess in any situation, the flatter the response the better.