I may keep the GPU overclock, or I may not. but if your phone is getting hot the GPU isn't the cause, specially if its hot while your not even using/charging the phone.
while I raised the GPU (from 200 to 300) the voltage for it is still the same. so thats not going to be getting any hotter then it was before.
you said you benchmarked both the stock ZVC kernel and Hyper? but 3D wasn't any better? even without anything overclocked the 3D scores will always be higher with Hyper since I enabled lg_dvs (in the GB kernel). Really the only way to see how its doing would be to benchmark 2 versions of the same kernel, one without the GPU overclocked and one with it, but I'm too busy to dick with that right now.
I see in your post you said you undervolted 1.3GHz, but that can't be done since the kernel doesn't support changing the voltage.
and btw, the kernel won't break the market =p