PM9 will be no problem. Full power ammo to the tune of 500 +P rounds through an Airweight like the 642 will be awfully tough on the hands, though a very few of our students have done it successfully. Neither is as bad as 500 .357 Magnums through an 11-ounce snubby, which I would DEFINITELY not recommend.
If your primary carries are the PM9 and the 642, I'd suggest bringing both and switching off. It would never hurt to have the SP-101 for backup if the Airweight revolver starts wearing on the hand.