I will certainly investigate the ULXD series.
1RU form factor is not a requirement. It is replacing 3RU worth of EV in the rack (plus 2RU of distro).
This system is not going to be run by tech students, but rather by athletic staff. Simplicity of operation is important.
"Simplicity of operation is important" in that environment so true.
Think about the operation of the handheld transmitter, I would look at models that have a nice easy to get to power switch. Small recessed push buttons or needing to open up the case to access the power switch do not mix well for multiple non tech users.
Chances are your old distro's would still work with a new wireless system in the UHF band. Look up the model and see if it is a broadband unit. If the distro is a Telex chances are it uses TNC connectors, you can get adapters to go to BNC or re-terminate one end of the coax jumpers.