I will use it to control lights in my home theater.
It will be connected to Crestron Adagio System.
The remote most likely will be ML 600.

My future plan is to add more Crestron lights but not right now.

Do I need a gateway right now?

Thanks

You will need it if you want it to talk back to a processor. The processor will need the gateway so it can communicate to the cls. The cresnet port on the cls-c6ex is for local keypads and expansion of it locally. The cls-c6 would use cresnet to talk to the processor which is the older version of the cls-c6ex and without the infinet. I would get the ex model and a gateway.

I agree!