The throttle coupled advance is based on the throttle position & not the actual RPM. I know this has already been mentioned but from a theoretical standpoint this may be as good as or better than advance based on actual rpm. Autos makers of yesteryear realized this and included vacuum advance (i.e. throttle position). Today timing in an auto is set based on throttle position, RPM, O2 & nock sensors, octane level, etc.
I'm pretty sure there is no performance advantage to either setup in our engines. An electronic advance should actually be less expensive than a mechanical setup. The component cost is less. The premium cost you are paying for electronic advance comes from "development." Because the cost is less for an electronic advance system, all future systems will eventually go that way.