I agree, try them out. I can't sew with armrests, so when I had a chair I took them off. I used the equivalent of a Gypsy Sit Upon [actually was a physical therapy cushion] which was really inexpensive back in the old days. I take it to sew-ins when I go now.
I finally bought myself a Swopper years ago and have loved using it. It is like sitting on a non-rolling balance ball, but I don't have to worry about pins deflating it.