I was looking at the GravityController and noticed that the two types of forces are switched
f = Strength / r2 / (float)Math.Sqrt(r2) * body1.Mass * body2.Mass * d;
f = Strength / r2 * body1.Mass * body2.Mass * d;
Also linear may as well be written:
f = Strength / r * body1.Mass * body2.Mass * d;
(r was previously declared)
Nitpicky, I know, but may as well keep it simple.