It costs 40 ammo extra, so it should be more powerful?
Isn't the goliath 100 munitions? And isn't the demo 90?
Goliath advantages:
1) Can be built at any truck
2) Does not require engineer unit to stand still and make noticeable action
3) Can cloak
4) Can move while cloaked
5) Good AoE
6) High damage
7) Relatively fast
Cons:
1) Makes some noise that can be heard while moving
2) Large target size, so can be hit if seen at distance
But really that's it. This unit is way too good for cost, and beyond that its annoying to add another squad wiping mechanic into a faction with high DPS units.