With -π to π radians you get absolute error of approximately 4e-16 radians. With -180 to 180 degrees you get absolute error of approximately 2e-14 degrees.

Even though the first number is smaller than the 2nd one, they actually represent the same angle once you consider that they are different units. So there's no precision advantage (absolute or relative) to converting degrees to radians.

Note that I'm not saying anything about fixed vs floating point, only responding to an earlier comment that radians give more precision in floating point representation.