Of Skids and Diff-Drops

Of "lifts" and "diff-drops"
I have a 1 inch diff-drop,it was performed when my ARB bull bar and winch were installed in order that the front drive line exits the diff perpendicular to it and horizontal with the ground leaving a clean line through the cv joints, no extra stress. It seems the top companies providing lift kits and levelling kits want this performed when their kit is used. Some do some dont.
Other companies suggest a diff-drop is not necessary unless a lift of over 3 inches is installed. I am looking at engine skid plates and see 2 different ideas at work here. Some work with diff-drops some do not.
I am putting my finger on the pulse of this FJ crowd in order to wade thru the bs!! :>)
A) Is a diff-drop  not necessary with a lift of less than 3 inches? If so I can remove mine, go back to factory bolts and install any skid plate I desire.
B) Is the diff-drop essential with any lift thereby limiting my skid choices?
Thanks everyone,
Steve Hope.