URC does, in fact, have dimmers from Lutron that are controlled natively via RF, but not RF direct to RadioRa. You could buy these (MRFA-600M-URC-Dimmer or MRFA-S6AM-URC- Switch) from a URC dealer for just your main theater and leave the rest of the house working with the RadioRA. Otherwise, you'll need that IR Kit or the RS232 kit (and a MSC400) to integrate with your MX3000.