Most of the time, I use a single Tridion development image for multiple purposes, including whatever time I get to spend researching how to do GUI extensions. When I'm flipping back out of research mode into doing some day-to-day development such as templating, it's better to have the benefit of the javascript minification that I might prefer to switch off while poking around in the guts of Anguilla. So just to make this switch as painless as possible, I've added the following code to my powershell $profile.

function SetGuiMinification($value){
  $filename = 'C:\Program Files (x86)\Tridion\web\WebUI\WebRoot\Configuration\System.config'
  $conf = [xml](gc $filename)
  $conf.Configuration.filters.filter |?{$_.type -like '*JScriptMinifier*'} |%{$_.enabled = $value}
  $conf.Save($filename)
  iisreset
}

function guimin {SetGuiMinification "always"}
function guinomin {SetGuiMinification "never"}

Now I can toggle backwards and forwards simply by typing guimin or guinomin (you may favour different words or spellings!)

Of course, this technique ought to work just as well to manipulate other elements and attributes in the XML files that control a Tridion installation. Perhaps you'd modify it to toggle the CSS minification too (removing the -like clause should do it).

If you have any good ideas for using this technique, please let me know.