I wheel with a guy who has diff skids, he's constantly hanging them up on logs and biting the sharp edge on same. Looks like the design of the ones you posted is a little better than his, so that may not be a concern. Unless you wheel in wicked big rocks, a diff skid is a waste of time IMO. Diff castings are thick, throw on a set of thick diff covers, grind the bottom edge flush with the casting, and you're good to go.