I have not. If the mash pH is too high, would it be enough for me to drop it with some citric acid (which I have lying around for other purposes)? Or would something like a pH stabilizer that I've seen at the homebrew store be better?
Based on my own experience and what I've read from many others, the pH stabilizer is ineffective and add a strange taste to your beer due to the amount of sodium in it. I don't think citirc acid would be effective because you;d have to add so much it might affect the flavor. I use either lactic or phosphoric acid to lower pH. You can also use sauermalt (Yeah, I probably dickchimped the spelling) to lower pH. But you'll have to have a way of measuring pH to know how much to use and if it's effective.