Not sure how far back the grid will sit, but with the "valley" I could imagine Moto3 bikes starting further up the hill which would mean that they could have significantly higher speeds than the guys who start at the front on level ground and then get going up a hill.
I do not think it will matter much with the MotoGP bikes with all of their power, but Moto3...
"Remember that an enduro tests the endurance of three things: your machine, your body, and your wits. Only one has to fail to keep you from reaching the finish line." Cycle World March 1966