A long time ago I was a ground engineer for a major airline and the fact that I had a PPL and IMC rating helped no end when you had to offer an aircraft for service with a defered defect It ment that if for instance the WX radar was U/S I would take a quick look at the TAF,s and if the forcast was for CB,s then swap the aircraft on to another service.
Now as an ATPL holder i find myself as the engineers preferd pilot when it comes to C of A airtests.
I think that the more that you can get the engineers into the air then the better service you will get from them , and if you can get them into one of the (very cheap) service flying clubs lso much the better.