I used both on the olive piece I'm working on (finished turning it today.
The StewMac scrapers took of wood much quicker which enabled me to remove some tool marks and undulations near the wings get the shape in the center of the top right with less work with the NRS and shear scrapers I'd use otherwise. Then I used a full-sized thin cabinet scraper with a shallow radius ground on one side, just a bit shallower than the inside curvature. This took off extremely fine shavings and made quick work of getting the entire curve perfect - then I hit it with 320 and 400 paper with a palm ROS and some hand sanding with a soft sanding block. I think it's about ready for finish now.
I've been using the thin scrapers for a long time now - these thick scrapers are a fantastic complement to the thin ones. No wonder people who make violins and such like them!
JKJ