Okay, here I go again, shoot me down if you must for my ignorance.
I started flying at Wycombe Park, UK. 3 types of aircraft mix in that airspace. Fixed wing, helicopters, gliders. All intensively flown.
And over the top (used to be 2,000' and above until the authorities granted a change) the jet traffic into Heathrow, and the politicians into Northolt, not to mention the military and the royals going in and out of Benson to the west and the tiger moths going in and out of White Waltham to the south.
Helicopters are different from all other birds, beware, they can rise vertically, go into reverse, etc. ( I have tried to reverse a Cessna away from a parking place but they stopped me in time.)
Blind spots exist particularly if high fixed wing conflicts with low fixed wing.
I do fly with a rear view mirror (to keep an eye on the glider on tow) but it doesn't help a lot. Too much vibration.
The real help in the Hudson corridor might be for the Feds to raise the ceiling for the VFR traffic? Like the regulators did over Wycombe? And then let the recommendations for keeping to the right up river, left downstream, , helis below l,500 and fixed wing between l,800 and 3,000, why not? After all, I can't imagine a cherokee taking off from a heliport.