Is the Discover 125M really that different from the Discover 125S?

Bajaj heavily pushes that the Discover 125M's 4 valve DTS-i engine is 'racing inspired' and promises better performance than 2 valve engines that are common in the class. Theoretically, the 4 valve design allows better breathing and higher revs. But, in a commuter focused 125cc bike, the real world benefits are debatable. While some riders swear they can tell the difference in responsiveness and top end power, others argue that it's imperceptible out on the road. The question remains open as to whether this more complex engine design affects reliability or maintenance costs in the long haul. Is this a real performance advantage that sets the Discover apart, or is it mostly vaporware for enthusiasts?