Certainly an interesting idea and I could see it working well for gyro based pointers. I think it would be good as an option but I am also one of the old school types who struggles with change (I still sort my media by filename as that is what works best for me in terms of quick navigation).
For it to work well you would probably have to increase the menu hierarchy depth, i.e restrict number of options on screen and therefore increase the click count in navigation terms. This could slow selection, but conversely it could speed it up due to less acuracy being required when using a gyro pointer.
So in summary yes would like to see this as an option, but please don't take away the option of linear menus
Sure, there must be user's choice. My whole point is that pie menus are more suitable for gyro remotes, cause it's always hard to stop at certain point in a list of 30 options.
Regarding number of choices... Having small number of options is IMHO a sign of well structured menus... So if one succeeds to organize menus into hierarchy with small number of options on each level, then is good for either menus...