More effective on higher difficulty levels as enemies will gain higher armor values. It's largely unnecessary on Easy/Normal, as enemy armor can be easily shredded with 1-2 Grenadiers or downright ignored.
Grenadier: Combines well with Holo Targeting and Shredder. The Grenadier can perform squad opening shots to apply these effects for others, while using the rounds to pierce before the armor is stripped.
Sharpshooter: 1 hit bomb Mechs/turrets a mile away. Easy to equip since snipers do not need protection vests. Can also feed kill streaks off Kill Zone/Serial perks.