I can't tell you how many times I've tried to double click on a text object in paper space and unknowingly clicked through to model space. I even set a keyboard shortcut "PSPACE" to quickly switch back to paperspace. "SPACESWITCH" is a variable that disables the ability to double click through viewports. set the variable to 0 and double click all you want. no more clicking through viewports and having to reset your scales. A fellow Augi made a lisp routine and I made a toggle button to activate it.
For the lisp routine go here. http://forums.augi.com/showthread.php?t=79006