Mathematically, there is no match. My post referred to the nature of the fights. There are a couple of fights where, due to fight mechanics, Momentum's uptime is seriously unreliable, aswell as potentially dangerous for your team mates. On pure ST, the difference between the 2 is simmed to be VERY small, hence there are cases in which Nemesis can pull ahead.
Remember that execution is not taken into account on numbers: if, for example, auto attacks are delayed due to the movement component required by Momentum's playstyle during the 200% buff of Chaos Blades, your dps loses effectiveness. It's very tricky to properly sim it. I have seen so many controversial information that i have come to this conclusion
Vanyali can explain it far better than i can :P