A coupla months back I also started using this AF-ON option and its been... interesting. Takes a bit of getting used to though, that's for sure, especially if you forget and thought your AF was still half-shutter. Lost a few shots in the learning process.
After that, it's been fun. Once AF achieved, just release the thumb, recompose and shoot. In Manual mode, the half-shutter metering is moot, so just shoot.
But complications arise when trying to pass the camera to someone else to shoot. They wouldn't know what to do generally, so must remember to reset back to half-shutter AF in those instances.
