I don't own a Leica, much less an M8, but since others without Leicas have commented on non-Leicas and non-RF I will too.
My first SLR was a Yashica TL Super. Match needle metering. I found it inconvenient to move the shutter dial while I had the camera to my eye, so I usually set a shutter speed I thought I wanted, then adjusted the aperture. Of couse, that had the advantage of letting me see the dof I was getting too.
Then I got the Fujica ST 901. I opted for the aperture priority with the Fujica as much for cost as anything else. I fell in love with it. I didn't have to be concerned with the shutter speed, it adjusted for the aperture and I could see it in LEDs in the viewfinder. As I was also doing forensic photography, I found I could set the camera on a tripod, compose, and set the aperture for what I wanted in focus, and let the camera take as long an exposure as it needed. Always accurate. I've loved it ever since.
The only RF I have with AP is the Olympus XA. I like it there too. Well, actually, the Canonet QL III 17, but strangely, I usually use it in full auto.