And I guess your T4 truck is deployed in base as well, isn't it?
What exactly is the argument about? This thread is about artillery, not OKW trucks.
I think that soviet artillery is fine honestly. It is fairly good, and can do its job well when not countered by recon + Stuka, but that is another problem.
The ostheer artillery on the other hand, needs help. It either needs less scatter than the ml-20, or to fire more shells (maybe 4 more). This way, they both have viable roles and are worth their price.
The Panzerwerfer needs as much hp and armor as a stuka. This will reinforce it's role as an assault rocket arty platform. If not hp + armor, it needs less scatter at further distances, or maybe suppression.