Suggesting that some error on a meter is tolerable because the shutter speeds are likely to be off
anyway is ludicrous. That's what shutter testers are for. First thing I do with any new leaf-shutter
lens or even curtain shutter in a small camera is to test the shutter speeds. It's like telling the highway patrolman that it doesn't matter what the speedometer said, because the weight of your
foot on the gas pedal is the real variable! I'll agree that the most important thing is just getting accustomed to your own specific meter and what results it produces. But the advantage of a spot
meter like the Pentax is quickly comparing mids, high, and low values. So you need linear accuracy,
not just hypothetical gray card value. Sometimes a meter which still reads correctly in the middle
nonetheless is due for a recalibatration at the extremes.