Happy New Year :-)
I would like to present my last idea, jhp, that's absolutely alpha and that requires "a special" component to be tested quickly ... and that's the reason of this post, a work in progress plugin for my byte family library, called overbyte Editor.
It's not a FireBug alternative, it's just a "quick and dirty" enviroment to test rapidly your scripts, functions, html pages and probably other.
overbyte Editor has some Extra special function, based on syncronous php interatcions or using jsmin to parse and test your code in one step.
It could open your files, save them or inject into a dedicated php file that should solve definitely bandwidth problems using both jsmin and gz features even on hosts that haven't zlib enabled (adapted version of GzOutput class without gzencode or gz_hendler).
You can read more about overbyte and jhp directly on Editor page, using About menu to read these and other Editor informations.
I'm waiting for your suggests, bug reports or comments,
bye bye :-)