I was wondering about that (in an airplane). With my 9C I can make the stick increments tie out to a series of even RMP progressions but the "stock" settings definately favor a natural exponential because the last 30% of the stick movement is a lot more of the engine's range than the first 70% on most of my models (IMHE). Maybe that's just the way I usually set-up my linkages??

On one of my models I took the time to tach out even linear RPM steps for the stick movement through idle, 25%, 50%, 75% and full. It was WAY more work than benefit as I usually fly more by "feel" than set positions.