[GeeTwo]

I agree that there are no rules forbidding connecting a CIM to a motor controller on a 20A breaker. However, unless you just happen to have a stack of CIMs in your inventory and no smaller motors, this is rather like getting a truck with a V8 engine then feeding it with a tiny fuel line. You'd be better off using a mini-CIM or other mid-size "unlimited" motor which will perform better at 20A.