From what I understand, version 4.6 eliminates the advantage of light weight players playing DL. For that reason, all previous weight limits are no longer valid. I am taking my cue from other leagues that have made the switch and Seth's Big Data League, and should our actual game play prove this incorrect, it will be changed back.

Addition to that out of my experience with v0.46:

If injury rate setting is normal (=100), more serious injuries might happen to light weight players out of position.