While the Shanghai-Beijing HSR was designed for 350 km/hr operation, it has in fact been operating at 300 km/hr for several years. You'll recall speed was reduced on all HSR lines due to concerns about construction issues.

In any event, they've just increased the speed on some departures on that line back to 350 km/hr. These departures carry a surcharge.

But no matter, 300 km/hr or 350 km/hr, they're all HSR.