The combat ability of the"Sharpshooter Squad" is NFG. Spend your 220 MP on a conscript instead.
I haven't tried the Barrage ability in 1.7 but 3/5 bunker health isn't bad damage. In 1.6 you received 1/6 or 1/8 health damage. Were you using Flare at the time? That is supposed to increase damage by 1/6 or 1/16.
The high cost of Mt for Artillery Strike makes this a dubious ability at best an worthless early game.
The notion that units are not supposed to fight and serve only a unitary purpose is Anathema to me.
On the bright side observers are very tough similar to guards but with heroic armor and i think 4 of them (2 squads)can take on volks or grenadiers...