Newbie with a '75 La Grande 31 ft

[silverloaf]

I dint mean to confuse you. I know of no better material than 2- part closed-cell part spray foam. Remember, the stud cavities are only 2-1/4” deep. It is best to leave It alone. The payback on replacement for few more R-value could be north of 150 years.

[Salty]

Along that line, I assume that tearing out all of the old foam isn't worth it because there aren't significant benefits between the original foam and brand-new closed-cell foam?

Precisely. There are actually alot of negatives about it and as you have surmised, no benefits beyond altering the wiring.