It gets the rockets on target a lot faster, which should make it significantly harder to dodge than the regular barrage. That should make it more useful especially for 1v1, where with the regular barrage it is relatively easy to hear it fire and move or retreat before the rockets land.
I understand your intention and I know the differences, but you removed supression for the low angle barrage. And it's a Vet 1 ability, so you have to shoot a few times in order to get access to this barrage ability. This already is a difference to compensate its more powerful impact. Why do you have to pay extra ammo on top? Katyusha and Calliope have the same barrage mechanism and don't pay anything. This low angle barrage seems more like an expensive downgrade atm.
Therefore I would suggest: Either add supression again or remove ammo cost. Both together make this ability useless in comparrison to the standard barrage.