Raul,
I don't go beyond about 1,000 hours myself. I am currently running a Transfiguration Orpheus L, and it does not have that many hours on it. I still have the Titan, and it too is well under 1,000 hours. I did run a Helikon to about 1,000 hours and gave it to a friend. He has used it quite a bit, and it does not show any obvious audible signs of wear. I can't say there is no extra damage being done to his records, but, his collection generally sounds great. I don't think he plays his records over and over, given that he has more than 5,000 records (pared down from closer to 10,000). I tend to play my favorites a lot more than he does, and my collection is in very good collection (aside from used records that came pre-damaged), but, like you, I don't push the limit on wear.
Many years ago, when I used cartridges like the Shure V-15- IV, V, I noticed drop off in sound quality MUCH sooner than I hear with the cartridges I use these days. Perhaps it is aging (me, not the cartridge) that partially accounts for this, but, I think those cartridges probably did not use as high quality diamonds. I had them examined by "experts" who never saw visible signs of wear. That makes me a bit wary of visual inspection. I've looked through microscopes at styli myself and I personally cannot judge what consistutes significant wear. The only kinds of pictures I saw that were clear enough, to me, were SEM photos. I bet not too many shops have access to that kind of gear.