The 500 we rebuilt last winter has the 0.2 inch ball joint spacer camber mod and the 0.1 inch bump steer mod at the tie rod / steering stem connection.  I posted previously that the tie rod was spaced by 0.2 inches, it is actually 0.1.  Anyway, my Dad purchased a 500 without the camber and bump steer mods and I rode both machines last weekend on the same rough sand.  I didn't notice an appreciable difference in bump steer.  The turning and handling of the machines were very different, however, with the camber modded bike making much quicker and more predictable turns.  (I especially noticed this trying to follow Q2W through the trails on the un-modded machine...  Lots of push when turning.)

I do not remember seeing anything on QRHQ about flipping the tie rod / spindle mount on the 500, only on the 250.  Does that help out on the 500 as well.