>Is anyone using _assign that much or what is the benefit of InteractiveChange over _assign?

First off, _Assign is associated with properties. So you would need the control's ControlSource set to the corresponding property. Next, _Assign doesn't fire as you change the data as InterActiveChange does. It only fires as you try to leave the control and the Value of the control gets written to the ControlSource.

If you want validation or actions to occur after each keystroke, use the InteractiveChange.