Spray foam on roof deck questions

was going to install blown in cellulose but a few contractors I've met with for other work suggested I consider spray foam. House is a high ranch about 60 years old, about 1600 sq. ft. located in New York. I know I need to remove all of the current batt insulation. The contractor who came to give me an estimate said he would spray about 8 or 9 inches of open cell foam. I have soffits running the entire house and a front overhang. He said he would use some old insulation and just stuff it under the eaves so the foam does not blow through the holes. Is this best practice or a quick fix? I have been under the impression from everything I've read and videos I've looked at that spray foam is 2 - 3 times more expensive than blown in cellulose. The price he quoted was about half of the cellulose estimates I've received. Red flags are flying at this point. Attic has plywood flooring for about 1/2 cover that we use for storage. There is no ductwork up there, other than exhaust from kitchen and bathroom fans. I also read that if spray foam is exposed it has to be painted with thermal paint or some kind of barrier. Is this required? He made no mention of it.

Your guidance appreciated.

Best... Steve

source https://hvac-talk.com/vbb/threads/2227539-Spray-foam-on-roof-deck-questions?goto=newpost