The problem with QR's on fixed gear bikes is that the horizontal dropouts and (horizontal) track ends allow the axle to slide around more readily than a bike with vertical dropouts, which don't allow for much, if any, horizontal movement.

The sudden torque of the relatively high gearing on fixed gears tends to repeatedly yank at the axles in stop and go traffic. Use tugnuts or chain/axle positioners or whatever they're called to hold your axle in place with the QR's. I'm not a weight weenie so I don't mind carrying my tools and a kitchen sink around with me all the time. I'm not a fan of hills either.