Yes, I also use the Fulltone OCD with my Rebel 30 combo it sounds incredible. I almost never use the Lead channel on the Rebel 30 since the OCD covers a very similar sonic territory as the Lead channel.
If you plan to use the OCD, I would highly reccomend using a higher voltage (18 v) supply to it. This gives the OCD more head room so that it acts more like a tube amp (cleaning up nicely when you roll back your volume control on the guitar, etc).
Lately I've used this to setup the Rebel 30 so that I use the Lead channel for more of a slightly overdriven bluesy tone instead of fully saturated tone, then I can use the OCD on either the Clean or Lead channel as a sort of nitro-boost. This gives me the ability to have several tones to choose from: clean, dirty rhythm tones, or full on saturated lead tones.
--Jim