Has anyone ever been approved to wear the Navy Warfare Insignia after transferring to the Army?

I would have to say yes, I was Prior Service MARINES Air Crew , went ARMY and wore my Wings , in Fact I got Gigged on my first Promotion Board for not wearing them I was told by my NCO that I could not wear them, he was told by the 1st Sgt after the board was over to look up the reg

I've never seen it. But then, I haven't known too many Army folks that were prior Navy. Submit all pertinent documents for HRC consideration to see if they approve it. Never know until you ask HRC.

AR670 has this to say. "3) Badges from other U.S. Services that indicate career fields are not authorized for wear, such as USAF medical insignia, or badges used to identify the duty, function, or classification of the wearer. Some examples are USAF fire protection, air training command instructor, security police, or the Naval aviation warfare specialist."