Agree with your caviats Antonius and especially the don't use unless there is a very good reason. The same syntax used in a note also works to overwrite a dimension, but generally speaking would be a horrible practice!
It is interesting that you say that you have a driving dimension, but I don't understand why you just wouldn't use that driving dimension to be displayed. I think if you want to drive using a parameter, it would generally be best to do so using relations...
