store interpolants for quantity.Discrete

I expect that the performance of quantity.Discrete can be increased vastly, if the interpolants created in on() or obj2value() would not be deleted directly again. Hence, it would be nice to store them in a property, whenever the interpolant is created. However, its forbidden to cat griddedInterpolants into an array. Is there some other way? Maybe creating an array of function_handles that contain the interpolants? And is it really worth the effort, or will this result in memory problems instead? Ideas?