I suggest taking the time to assign parameter names to "user-defined parameters" instead of assigning them while placing the dimension. If the name of the parameter is assigned to the model parameters and the feature containing that named parameter is deleted, then that parameter name is also deleted, and any formulas or iLogic code referencing that parameter name is broken. However, if you create User Parameters and then assign the model parameter Equation to the user-named parameter then it doesn't matter if features or sketches are deleted.

Great info, Jim. Nice car.