And I agree with everything you just said. I agree that it would be sensible to mandate replacement of a vacuum pump at 600 hours in IFR cat and without a second attitude gyro (not a T&B) powered independently. That would be sensible. Overhauling all 4 of my magnetos every 4 years is not. If one fails in flight, I just get to look at my engine monitor, switch the magneto off and continue to my destination. I have 3 others (which get inspected every 500 hours because it is a good, sensible idea), and a whole spare engine. Where is the risk?