When I put a R20 in place of a D20, I appear to get unregulated voltage without changing the module type in the CEM3. Is there a reason to change the module type to Relay in the CEM3?
You are quite right. The relay is a true mechanical relay, so it will switch on and off without providing any dimmed voltage.
The only reason you would really need to change the type is if you need the relay to turn on or off at an exact specified threshold like 10% for example - you can do that when you've set it to relay mode. But if you're ok using 0% control to mean off and 100% to be on, no need to change the type.
Thanks for confirming. 0% / 100% works fine for me.