Cleaning the grease out of the differential is not a pain in the ass its actually easy, what I do is get a gerber food container, you know those small clear glass ones, and the stick all my differential and its components with the grease still in it (well get as most as you can with a q tip), then I spray some Aerosolve II spray in it till the spray liquid fill like 25% of it then close the lid and shake it up and then dispose the aerosolve liquid and take out the differential out and rinse it with water, then its like new and now oily and greasy and ready for some more grease.
EDIT: when using aerosolve be sure to use gloves and eye protection. When that stuff stayed in my hand for like 1 min my hand got irritated. Eye Glasses cause I'm sure you dont want to get stuff like that in your eyes. And do it outside cause aerosolve is strong and will stay in your house for hours/days.