The cylinders I use are rated for 250PSI, but I only have 2 customers that run the machines at that pressure. Running the cylinders at 250PSI has some challenges so most people opt out of that pressure range and stick to 40-150PSI from standard shop compressors.
There is a company, I think out of business now, called PNEUCO. They made a pneumatic press brake using an airbag/bladder. I looked into it when I was designing my first couple prototypes but never took a shot at designing a machine using air bags. I have never used one... Without a piston I would guess the force would be non linear, and they would have no possibility of being double acting?? They sure are cheap though... Might be worth a shot at designing a machine that can overcome the challenges of using an air bag.
Have you ever seen or used one in a pressing application?