It would be less effective than a Hunting Tiger and they proved almost useless in the later stages of the war.
It couldn't have moved across bridges. I would have required tremendous amounts of fuel. It would have had to hide in a railroad tunnel to reload like
"Dora". Who would ever buy one? Ever bought a SturmTiger?
I have a scenario...only one...that includes a SturmTiger. It's called HSG EW Tiger by the Tail.
You can get the scenario here
HSG EW A Tiger By the Tail
if you are interested in trying to fight with something similair to this beast in a somewhat balanced scenario.
Good Hunting.
MR