I found that with the make up of my shoulders this diagonal arranged unit still could put some pressure on the neck, sideways. I prefer to have my neck unencumbered. Besides, getting the camera into shooting position might be a bit inconvenient - then again, I have not tried it. With the carrier it is right there in front of you, and it does not bang against any obstacles on your side (gates and such). The con is that it is a bit wierd getting the cam out of the holster, since you have to turn it 90° in order for it to release. It is a safety feature that ensures you cam does not accidentally come free. If I am not mistaken, cotton carrier has a neat video showing a guy running with the setup, and clearly the cam does not impede that - i'd not think this could be done with AT's setup as easily.
What I like about the BlackRapid strap is the camera hangs right at my right hand and quickly goes to the eye, plus it hangs out of the way (on my side). It can get bumped, so I just always have my hand on it. It cannot come free unless the ring that screws into the bottom of the camera comes unscrewed. It will not fall out of the D-ring because it is a locking D-ring.