When I was out in Oregon a couple of years ago I visited Hank Holzer's shop. He was using his stroke sander with a flexible belt and shaped platens to sand the inside and outside of coopered chair parts. It is also possible with a slack belt to sand moderate curves in the longitudinal direction. So the stroke sander is more versatile than you might think at first glance.

Years ago Fine Woodworking had an article about Joe Tracy up in Mt Desert Island which included a description of him buffing out the finish on a run of tables using a stroke sander with an old belt covered with scotchbrite. I wonder if anyone knows of a source for such belts readymade?