Yes, magnets do help with he-ne lasers, though I'm unsure with diode lasers. I pretty much doubt it since it all takes place in a confined area and not through a big gas tube lasing medium. I had the pleasure of meeting Sam a few times and he's a heck of a guy. In addition to magnets possibly helping, temperature plays a bigger role in he-ne lasers as well as diode lasers. I saw an experiment Sam was helping a professor at Stony Brook with, and it involved wrapping a he-ne laser with magnet wire, except reversing the turns each way. Basically, the whole thing looked like a solenoid, but the magnetic fields actually cancelled out, and in the end, it was just a heater. This was then wired up to a heater temperature controller circuit he built in order to stabilize the laser.