These are two tiers apart: the SC3 Pro is a top-tier flagship topping fidelity and build, and the Sport 9 is a 9 Nm entry base at roughly a third of the price. One is for a no-compromise rig; the other for a first direct drive.
So shop your tier. If you want the best feel and build, the SC3 Pro delivers it. If you are starting out, the Sport 9 is a good, cheap entry with the Simagic ladder above it. The gap is the whole story.