The problem with the scott is while the barrage is great, it bugs out (cancels) if you stop scott at any point during the barrage -- it's not possible to fix this bug. Thus, if you start a barrage and the enemy forces you to move while barraging, you need to keep moving.
It also doesn't help that the barrage has a 60-second cooldown.
I've said my peace about the mortar, so I have to derail now. I don't see how you think the scott sucks because of a bug that doesn't even affect it's best strength. Honestly the scott is one of the shining stars of my army now. I get people doing all kinds of stupid risky crap to kill it (like overextending panthers and king tigers into m6 mines). One game I got over 80 kills with a single Scott that survived the entire game! I actually thought it was in danger of being nerfed. It does miss a lot, but keeping it behind an infantry wall is extremely effective. Once it hits it's pretty damned devastating. Sometimes on-par with the difficulty of dealing with a brumbar, but cheaper.
The barrage is pretty crappy and I really only use it when I'm desperate. It misses small targets, so it's only really useful on OKW buildings or immobilized heavies. You can even increase it's accuracy by manually targeting squads in a specific manner. When shooting at moving squads the shots will miss usually, but they will land just behind the target. So, by manually targeting a blobber's point squad, the shot lands in the middle of the blob wrecking like 5 guys at a time! I get these things to vet 3 all the time in team games. 1v1 tends to have smarter players, so you may not get opportunities to splash shots in the middle of blobs, but it still will significantly help you win infantry engagments. Each shot is like bundle grenade.
I would like to see the cooldown on the barrage released, though. The barrage sucks, but I would like to be able to use the smoke more often. Sometimes I use it to cover squads capping vp or covering teamates armor.