Guessing CFI, MEI, CFII for most- I heard a jet contracting firm started this movement- also an argument for an ATP based on Mil experience again....
I have a CFIG, so I did the fundamentals of Instructing way back, and I hold an ATP-this would be a swell way to add some ratings w/o much add'l effort or study- Floatplanes and Helo's are where I'd like to spend my VA bennies, not on CFI certs!