Models follow the same laws of physics as manned helicopters, so don't automatically dismiss an argument just because the argument mentions them.
Regarding angular momentum, the path of each rotor blade can be characterized just as accurately using the concept of angular momentum as it can without it. It's just apples and oranges... 6 of one, half dozen of another. Angular momentum is just an extension of F=MA.
I write rotor dynamics code for full flight sims (several of you have probably even flown them), and the results are identical regardless of whether they are based on angular momentum or not.