SD & Sac lead the way in what sense? Freight + Light Rail? That's not SMART. A better comparison might be the North County/Escondido line, though that's still light rail + freight (just diesel-operated instead of electric). And Sacramento is a poor comparison because freight service along their light rail lines is completely separated. Since SMART's DMUs will be FRA compliant, a better comparison might be to Westside near Portland, or the RDC-operated lines in the Dallas area, or the new lines Denver is cooking up for airport service.

Frankly, not many truly comparable lines (DMUs, shared with freight, FRA compliant, owned by the commuter agency) come to mind. Most miss on at least one of those criteria, with the most common miss being FRA-compliant DMU use - actual trains are more common for commuter lines.

That said, IMNSHO SMART isn't so smart when it comes to cooperating with the freight line, which almost certainly will pay something for its operation (SMART will need the revenue however it can get it). I wouldn't be surprised if somebody figures out a way to get FRA involved again if this nonsense continues.