I prefer 3:30 IWB all around but I have AIWB a few times in a JM Custom G17 holster made for a 17/22 and a G19 length Dark Star clip holster. Too easy. Also once or twice with a Fricke trigger clip w/ lanyard.
GJM observed with the full size grip he could carry it lower for concealment of the full size grip but still hit the grip well in the draw. Good observation. I pretty much always gravitate to the lower/lowest carry for concealment.
The 19's obviously shorter grip should give it some advantage of course.