I think Neuro mentioned hanging his 600/4 on a BR strap.
Here's what I've thought about getting for this type of situation (but haven't bought, yet):
I have Blackrapid straps as well as the Kirk security strap. The Kirk strap works well if the lens is the only thing you're carrying. Frequently, I am carrying the lens and wearing a backpack, and that does not allow the Kirk strap freedom to slide, meaning you cannot just raise the camera to your eye. I think the design intent of the Kirk strap was to carry a second large lens for swapping.
I usually use a Blackrapid Sport-L with the 600 II. When they came out with a left-handed strap, I didn't really get the point (except to make Ned Flanders happy), since you need your right hand on the camera to press the shutter button. However, a left-handed strap is perfect for use with a supertele, since I lift it and continue supporting it with my left hand while using my right hand to control the camera.
i wouldn't trust an arca swiss clamp in that application.
What are you going to do, get some boat anchor chain and weld it directly to the lens?
The standard Arca-Swiss clamps (RRS, Kirk, etc.) can hold far more weight than a supertele lens.