Nothing wrong with using a MultiView, if the modules/forms in question are simple. But if any of the forms gets complex, you are better off separating them into different controls.
I used a derivative of the example presented by InDyneInc in this link. They use the concept of a "switchboard" main control, under which, according to your logic, parameters, etc. you load the other user controls.
The way I have done it, and I have never ran into the problem with v13wstate, is that I have no controls at all in the switchboard module, which is the registered View control for the module. This is another advantage I see with this method, you don't have to register any of the other user controls, just the main View control.
Hope this helps.
Carlos