I have very similar issues as you in a similar setup: ~30 blue switches, Z2M, all controlling Hue bulbs. I, however, split my network into two to reduce the number of devices in each. That cut waaay down on the random errors and general stability, but did not fix binding.
The most frustrating is the binding issues that you note in your (2). I played around with sniffing and documented a bit here, but still need to follow up on that after the holidays.
I wonder if anyone is running blue switches bound to hue lights at a similar scale that is actually having success? From what I’m seeing in my linked thread above, the network flooding appears to be due to the large amount of devices trying to talk over each other with the Blue’s sending a whole lot of broadcast messages.
Also, @bgreet- I see your direct message about setting up a sniffer- I’ll try to get around to replying later today.
edit: I only have about 30 blue switches, not 50… I don’t know why I wrote that at first 