Being overtaken on climb
The dirty secret is that while on climb you can be smacked by faster traffic coming up from behind -- and at certain angles the guy coming up from behind will not see the climbing traffic.
Would climbing in the middle of the Hudson keep you clear of transiting traffic over the banks?
Remember that transiting traffic is not cognizant of the heliport locations or their landing / takeoff patterns. Yes, one could put them on the map but do you prefer transiting pilots with their eyes outside or on the map?