RE: 3rd Axis necessary?
I'm not even sure it's overly necessary for 3D in all honesty. If I put some time into shooting, I maintain my grip, etc, I'm not sure where I'd personally benefit from it. I've shot from elevated positions for so long, it feels natural, and I've never had any issues shooting from an elevated position. The UPHILL now there may be an application, but I've not seen it yet.