The best arty is the one that is precise ( or covers a lot of ground simoutaneously) and packs a lot of damage - like calliope. That's why calli is often game changer - one salvo and enemy blob is decimated.
I only use Roadblocks as spots of uncrushable green cover for PGs that take ages to build. They're pretty crap.
OSTHEER IS DONE WHEN IT'S DONE!