I dabble with 2006-2012 F550's that are salt trucks. I see lots of salt damage. I change calipers, which are dual piston very similar to ours constantly. I have been getting various brands of rebuilts, and astonishingly the best come from Centric. Right down to the quality of the copper washers for the line connection, I am very impressed with Centric. I have also found that the "brake lube" that comes with some kits is very similar to dielectric grease, and I've been using that with some success.
At home, unless I'm going to do a job like changing all 4 calipers, I buy the little pints. They stay sealed and fresh until I need them. I also bought a brake fluid tester- works real good. It looks like a pen light and takes AAA batts. One end has 2 metal prongs and LED's on the other. Just dip the prongs and see the moisture content.