To be frank, I've never seen a Ballistic Vest with over 14 Threshold, and that sure wasn't on level 5, more around 15.
Still, a sniperrifle can easily still punch through that. What's the point in a vest if a metal armour does just as well?
It's too heavy for evasion, not used as a Psion (at least not with Ceramic plates^^), so I'd class it as heavy armour.
As such, I don't quite see the problem.
I mean, most actually dangerous enemies for most of the game use snipers, grenades, or energy weapons...