I want to cut some sheet steel. I expect I might have to make several
feet of cuts at a time, and I might need to make ten feet of cuts in a
few months. I expect the material will be 304 stainless or similar, say
around 22 ga. (0.031 inches) give or take 20%.

Would it likely be unpleasant to use a muscle-powered nibbler? Should I
just plan on a pneumatic nibbler? Would I likely see much difference
in the finished product? I'm not set up for air tools right now, but I
could probably rent something ...

Please advise.