Beagle
As you said you are "expected" to follow instructions from the RAC which is different from doing what you want failure to do so would mean that the service would be terminated.
The subtle reason is that in a FIS you are responsible for you own seperation In RAS the controller takes on that responsibility. Failure to follow his instructions would mean that he would be unable to be responsible for you.
The only difference is that in CAS failure to comply with an instruction could lead to a prosecution failure to comply with a RAS would mean termination of that service. But realistically you are expected to follow both so not quite the do as you want in class G and that was what I was trying to clarify. You can but dont expect a RAS if you do.
Pace