IMO E3 doesn’t have a sibilance problem, rather a problem with unnatural forwardness in the upper mid. The issue is less obvious with warm tilt gear but it’s still there. I tried a few EQ to fix but EQ ended up degrading the mid quality generally. I also tried full set of DCA tuning pads, TP, stocking, and other damping materials to varying degrees of success but none cured or mitigated the problem enough to my liking.
But even with that problem E3 is your only option if you want closed (that sounds open) and can’t stand the anemic bass/lack of emotion/lack of dynamic from Stealth.