I'm just curious, you've done Vizier HC or talking about talents in general? Attenuation in HC is pretty different from normal, and in addition to
Sonic Ring (hits for 140-160k) there's
Sonic Pulse (hits for 280k-320k)
Those numbers reduced to 70k-80k and 140-160k with feint, to 49k-56k and 98-112k with talented feint (obviously elusivness already better than cheat death), if you really screwed up - glyphed CoS reduces those numbers further to 29k-34k and 59k-67k (all those numbers before the armor values btw)
Believe me, 100k HS heals won't save you there - you need to
prevent damage taken.
Not to mention that you don't need glyphed CoS anywhere else during this fight - it's oh shit" button for P1 and "must have" defensive CD for p2 (for
force and verve)
If that glyph saved my ass on more than one occasion (i was sole survivor on our 1st Vizier HC kill, for example) - then i'm really
need this glyph for this fight.
There's no choice between Cheat Death and Glyph of CoS. Choice is between Elusivness and Cheat Death, and there's no any choice there, tbh.
Elusivness >> Cheat Death, end of story (not only for Vizier HC but in general too).