I haven't kept up with the brake fluid industry and was searching for a good article on the subject. Here's a nice article I found that gives an excellent 1 page overview of the whole thing.
I don't know who this guy is, but he at least seems to know what he's talking about. Hope it helps.

Brake Fluid Article

 

flushing and refillng avoids all kinds of problems.my driver side caliper froze up .scared the hell out me. regreased the pins refilled with fresh fluid. not one problem since.