To overclock or not to overclock, that is the question

I have an Asus ENGTX 460 TOP 768MB which come with a custom cooler and tends to stay very cool.
I'm at 1.075v and 919 MHz core, 3980 MHz memory (I can't go any higher on the memory with the Asus SmartDoctor). My temps for the GPU don't top 56 C with the smart cooling enabled. (That's around 69% fanspeed under Furmark/Tessmark).

I can go upto 1.1v on the voltage and 1050Mhz on the core with SmartDoctor.

The question is, should I go any higher on the voltage and the clocks? Anyone with a GTX 460 gone this high without problems?

Looking at the temps I feel like I should be able to easily. 56 C @ 100% seems like nothing. But then again I don't really know what the max safe voltage for the silicon is, and as that kinda information doesn't seem to be around on the net I suppose the experience of other OCers would be really handy. I'd like this rig to last.

Then again seeing as Asus' own utility allows overvolting upto 1.1v it can't be terrible right? I mean, I am guessing their programmers wouldn't put 1.1v mod on the software unless their engineers said that voltage is something the silicon can take (given that the heat is managed).