Yeah-- I guess "mathy" in my head implies a passion for the subject, not merely aptitude for it. (I've got one of those kids, too-- she's GOOD at math, but isn't passionately engaged by it.)

Sounds like a nice system for kiddos that truly do think of math as a fun elective opportunity. Equally good that it's not mandatory for kids who don't, too.

Schrödinger's cat walks into a bar. And doesn't.