3rd party cases better for signal than bumper?

[iphoneZ]

Has anyone with a third party case done some comparison on the antenna / death touch performance vs the iBumper? Pls share your results, curious to see whether other cases improve the signal more than the bumper

 

[mutantblack]

I don't have bumper case but I do have ebay tpu case and it does indeed help me from death grip. Never lose signal by holding the phone wrong.