The Spark runs bigger than the Scale, and the Genius runs bigger than both.
Check out the stack and reach measurements on the geo. charts on the website. Also get in a test ride if you can. If you keep the same size, size down the stem, which is likely Scott's intent by increasing the reach as bike travel increases.
A forum community dedicated to Mountain Bike owners and enthusiasts. Come join the discussion about bike parts, components, deals, performance, modifications, classifieds, trails, troubleshooting, maintenance, and more!