Today I thought of another option around this idea.
3.
Another useful option would be to have little tabs, one for each saved
state.
This way the user would be able to see his/her website at different
states, just a click away..
There would be and option to affect a state to a given new tab.
Check this mockup I made :
http://img3.imageshack.us/img3/2500/firebugstates.png
You can see a new bar with different states ("body content removed" or
"State #4" are examples of tabs named by the user..).
I think a bar with tabs would be even easier to browse between states.