I have tried 4G twice with different strings in between. I won't use it again. Hard on the arm and no free power. I hit the ball hard and I am used to polys that give you that extra snap when hitting a hard serve or flattening out a ground stroke, this string does not give that. And maybe that was the design goal, a string that behaves exactly the same no matter how hard you hit it.
But in summary, to hard on the arm and no benefit to my game. I'll stick with Genesis Black Magic.