I see a problem with the recently added always updating "benchmark" results: when you add or remove GPUs after you've done the benchmarks the results get messed up, as the currently running algos will change in values, whereas others will not. especially when adding GPUs this will move the current top algo(s) up ahead above the others so they never run again and therefore also don't update their results.
maybe an option to disable the updating after benchmarks could be added?
you can just rename your current gpu groups, then it will have to benchmark them again.
For example I use a group with 3x1070 (devices 0,1,2), if I want to game on my card that has a display on it, i just copy a different config.txt where I have a group named 2x1070 with devices 1,2
EDIT:
that said, I was also wondering about what to do when I change the overclock on my cards, I sometimes run them at 64-75% power limit (when I sleep I want them quiter), and sometimes at 75-89% PL, so hashrate changes a little, so when downclocking it's more probable it will change algos more often, while when upclocking, it will change algos less.
For that scenario, I would just have 2 instances of MegaMiner installed on my PC. One that is run at night that keeps all its own benchmarks on the lower power setup, and one that runs in the day with the higher power.