That's clientside so not what zyp's on about, but +1 to that lol
As for this suggestion, I agree on a headshot's secondary benefit being a quiet kill, however I'm just a little on the fence as to making it too quiet since every time I've heard the splatter I've also heard the drop of the body and weapons, I have to be real close for it to noticeably louder.
So all in all my experience is they're just as loud as a silent kill, but if possible the distance cut-off could be reduced, the quietening of the HS sound either way would be a negligible change in terms of people noticing if they're paying attention.
+1 cause it's harmless and benefits, in a small way, a sniper using a sniper like a sniper, rather than beaning a dude in a crowd and ducking away