I'm using a modded bios with my two 7850's. It works like a charm, and there were very little chances of bricking the cards, since they have a dual bios chip. If something went wrong I could have switched to the secondary bios and reflash the primary with the one I'd saved. So if your cards have dual bios, I'd think it is not very risky to try a modded one.
I'm afraid I'm becoming an OC junky too! And since I'm such a noob (basically ignorant) I do things without much regard for involved risks. So far I haven't bricked or fried anything (fingers crossed).
Ignorance is bliss some times, or so my GF tells me!