Brake stay mounting point

[m in sc]

same on a few of my bikes, way better way to do it. IMHO, nice and clean.

[Dvsrd]

This kind of setup is called a "floating rear brake" and was pretty common on MXers years ago. The idea was to isolate braking forces from the rear suspension, and let the suspension work the same way whether you were braking or not. The ideal setup would be a paralellogram shape. So the potential advantage is a slight improvement in rear suspension when braking.
Disadvantages would be possible conflict with exhaust system, added weight and complexity, joints and bushings that need to be lubed and maintained. It would also be very difficult to use a brake stay for a rear drum brake, instead a brake cable would be used.
If I was to build this kind of setup, I would use ball joints at both ends of the static brake stay, and some kind of bushing where it pivots on the wheel axle spacer. A ball or roller bearing is neither suitable nor neccessary. A needle bearing may be, though.

[m in sc]

The ideal setup would be a paralellogram shape.

yup, and neither of those seem to be at first glance.