I can't hear much above 12k, from memory, but I'm still not concerned.
From my perspective, the highs I can't hear in isolation don't matter as they're never discreet sounds or instruments; they're always embedded within other sounds.
I believe the character of sounds reveals their HF content.
So for mine, I'm happy to deal with those instruments in the context of how good they sound to me, always bearing in mind that radical boosts such as the one you referred to will likely bring me undone.
Further, I hardly ever boost anything; we're talking a couple o' boosts in 20 years of mixing. Seriously. I'm a cut man all the way.
Just thought I'd share for the heck of it.
