I just did the Tech Wash thing recently and was blown away at the amount of dirt that came off. I did the whole process in a 5 gallon bucket (a couple gallons of water, right amount of Tech Wash, soak, agitate, rinse, rinse, rinse).

I also opted to do a down jacket and down sleeping bag with a similar product designed for washing down. I can't believe the amount of loft I got back, particularly in the 10+ years dirty sleeping bag.

A very worthy investment.