I’m surprised this thread got this far without mentioning mold and mildew issues.
I’ve built and also torn down several grow areas over the years. In every case where batt insulation was used , there was mold inside the wall cavity. Now, I do live in very cool/ cold climate where its extremely cold during the long winter season. And that cold blasting the out side of a 2x4 wall while I’ve got cranked up to 80 degrees inside the room, well, that’s where the condensation starts. This may not be an issue on interior walls but if you are on any exterior walls this could be an issue.
IMO... the foam insulation seems worth the extra investment. On a2x4 wall with batts I think you can only get R13 or maybe R15, foam gets you R21, and less potential mold issues.