This is simply wrong.
Just lanched a test. ML-20 barraging LeFH, LeFH using counter barrage.
1 win for ML-20
1 win for LeFH
8 draws (both survived/both destroyed/out of crew).
Were you testing them at max or medium range? Did you place them by a place that could reinforce? How many barrages did it take?
Just saying "Oh I did it this what happened" tells us nothing. But if you took the time to look at the stats you would see that literally the only thing the LeFH has on the ML-20 is more shells fired; 4 with no vet and 2 with vet. Seems pretty lackluster of an advantage for being much much worse in the damage department while still costing exactly the same.
This also doesn't take into account the design of both factions, with the LeFH not exactly drowning in targets due to the fact both Allied factions are not designed around defensive play.
EDIT: The correct way to use the LeFH is German Mech Doctrine. Recon with smoke drop, scopes, and Command Tank to reduce damage from incoming artillery. Also you can't chose what target counter-barrage fires at, so having it on all the time is a very bad idea.