Same line, same encoder, so wheels and software carry across - this is torque and refinement for $120. The Alpha EVO 12 is 12 Nm with the zero-cogging 5-pole servo that reviewers rate as the smoothest in the mid tier, and it scores higher on our rubric; the Sport 9 is the cheaper 9 Nm rung.
For most drivers 9 Nm is enough, so the Sport 9 covers the budget end well. Step up to the Alpha EVO 12 if you want the extra torque, the active cooling and the cleaner signal, and the $120 is worth it. Neither strands you - both are on the same Simagic ladder.