Do whatever feels right for you, and if you've got something that's working fine you shouldn't change it.
But I was taught to use the rear brake only at very slow speeds to avoid the chance of grabbing the front brake if you have to stop in a hurry.
Eg if you take off then the car in front suddenly stops, if you have both feet on the ground there's a chance you'll hit the front brake too hard (esp if you're also trying to work the throttle with that hand), making it a lot easier to tip over.
So in this case if you had your right foot on the rear brake and your right hand only on the throttle, you'd have less of a chance of this happening.