John, I've heard of some people using "just off boil" water in their Moka pot to decrease the amount of time needed on the stovetop, thus decreasing the exposure to heat for the beans. Also, pulling the pot from the heat while the brew is still gurgling out will help as well. I've only tested this twice, and didn't perfect it so of course... ymmv.
I've tried the second trick, but not the first. Thanks for the suggestion! I'm an infrequent Moka pot user, as I feel like they need babysitting, and if I'm in the mood to make a real ritual out of it, I'll usually make Turkish or Espresso instead. I may have to experiment more with Moka pots.