The Dead-Squat Bar is great for farmer's walks, but also for the dead-squats themselves (trap bar deadlifts which hit the quads more), bench pressing, overhead pressing (you don't have to go in front or behind the neck - feels good), rack/pin work (it's long enough), stiff-leg deadlifts, lunges and other unilateral work, etc.
So, very versatile.
Ben Bruno has some good articles and videos in the archives on trap bar variations.
Personally, I find that the Dead-Squat bar is better for farmer's walks because of the 15 degree natural handle angle and the fact that it allows the hands to be out wider rather than straight down as with farmer's handles or dumbbells, which bumps the legs more -- especially as fatigue sets in. That hands-wider position seems to hit the traps more as well.