The Leviton dimmer instruction set comes with a specific disclaimer " Large clustering of communicating devices in a centralized location (ie a closet) is not recommended."
This is exactly my installation requirements. Any opinions on if this statement is factual?
Of course it is factual. Radio signals interfere with each other, so if you get enough in a real close proximity and there will be interference.
Now, how many is too many? How close is too close? And how much interference can there be before there are significant enough performance or signal issues? Well, it takes a lot of work and spectrum analysis to answer that.
50 switches in a closet? Yeah you'll probably have issues.
The house was remodeled 15 years ago and used a early home automation system from URC. Most of the switches are centrally located in 2 closets with "controllers" in each room for local control. I have to replace all the switches because they don't support led bulbs.