The Lectrosonics Digital Hybrid is different in that it's using digitally encoded audio over an analog carrier, so none of the disadvantages of pure digital wireless systems.
There are a bunch of artists using Lectrosonics gear to get from their instruments to their pedalboards and amps with no noise issues.
I would imagine it's the same with the Crown 311.
Digital UHF is quite a bit different, actually. If you're using something like Shure ULX-D or Axient Digital you might notice a hissing noise in the signal if the pickup is being affected. The Crown 311 headsets we still have can only be used with analog wireless, for instance. And we had to replace some of the older lavs and handheld heads.