Very wise advice.

I'm on my original L03A's and pushing 7000 miles on them. They still have a lot of life between where they are now and the 0.5 mm that Shimano recommends replacement at. And one does need to do that because that is the thickness of the legs on the spring that goes down the sides of each pad.

I bought some L04C metal pads when I was at 2000 miles just to be ready for the 4000 miles replacement others told me they got. Since I'm not a high mileage rider, they are now several generations out of date. Not that it really matters. They still will do what they were made to do. However in the mean time I've changed my mind about going to metal. With the long life of what I've gotten out of the resin, I just plan to get what ever the newest generation I can find of resin when I get almost to 0.5mm.