Even if you can get an accuracy of 1 deg with sensor fusion it is not good enough.

Nonsense.

It is interesting that for a falling inverted pendulum, the rate of change of theta (tilt) is proportional to theta (for theta << 1 radian). This follows directly from the equation of motion about a point of unstable equilibrium:theta dot = sqrt(g/l)*thetawhere l is the distance from the pivot point to the center of mass.