dah! I can't believe I missed this thread!
I totally agree with Mike here... From a buffering standpouint, I think liverock really does nothing, my tank pH rarely drops below 8.0, so I'm not going to be disoloving liverock any time soon.
As far as the nutrient loading, well, I am a HUGE fan of rock cooking, but only if you do it correctly, which really just means lots of time, AND lots of water changes. As bacterial tugor forces out the nutrients you get a nasty muck on the bottom, that just puts the nutrients right into the water column. Gotta do water changes to remove this and make that bacteria strip the rock clean. I just use powerheads and a heater (the warmer the better to make that bacteria work faster). I change out the water (100%)weekly or twice a week, whatever I have time for.
I don't plan on changing out my rock ever again to tell the truth. I'm hoping to strip enough crap out of the water with my bare bottom, high turnover and oversized skimmer that nutrients don't build up in my system at all. We will see how it goes