This is actually the only thing I keep the webdev tools addon around for now, everything else I used to use it for is either in firebug or I've found other implementations for (eg W3C checks I use unicorn first which I have a saved search "key" for).
But, this is---for me---a one time thing, after I've made all the changes I want and things look great. It makes the CTRL-S, Alt-Tab, Reload procedure that was originally described only need to happen once, instead of lots of times in rapid succession.