I changed brake fluid at about 20,000 miles, roughly 18 months. The fluid was dark but not milky. I found the same mismatch sizes up front. Used the Mity-Vac and found the 8mm side sucked air, but the 10mm side was nice and tight. Brake feel improved dramatically with the new fluid. It is amazing that something as small as the quality or age of the brake fluid can make such a difference.
2013 Cross Country Tour: Custom paint, stage 1 exhaust, Lloydz Hi-Flow air filter, cams (HOH-VM1-DR), timing gear (HOH-PTS), Power Commander V, Auto Tune module, Gustafson flip shield, OEM passenger backrest with Cycle Ops luggage rack, Vic HID, heel shifter, Rockford amp, Infinity speakers all around.
2011 Cross Country: Burnt and Traded