For Mephisto runs use most MF u can afford, without drastically reduce your "power". U need to have good gear to kill Mephisto fast, so u can do more runs.

For Pindle i don't like a bunch of mf. i use something between 300-350. Increasing MF on Pindle gives u thousands of Rare items (Elites) which is not the point here.

Use the same strategy as Maphisto on Andariel, Diablo, Shenk, Baal, Pit Runs, etc ..