Stealth can be used for a clutch revive or to go for an objective. But an optimal Stealth scenario will be to position yourself at the back of the pack of enemies, charge up the eviscerator, and heavy attack into the back of that crusher/mauler/whatever big threat. Then clear the wave from behind. your stealth is gonna be up every couple seconds which will drop aggro thus turning them around toward your team and giving you backstab kills to reset it again. The damage from the other branch of shroudfield is negligible and only on the first hit which then isnt even being used if you use the stealth for a revive. the utility from the longer invis timer is much greater and allows you to position better and make it to your team to revive them without dying on the way.