Uuuhhmm. Captain.. and Nandric. I read your posts and get the point (pun).
The way I see it is that stylus wear occurs slowly over time. Therefore, to simply say, use your ears to tell you that if the highs become muddy, or the bass does this or that, then you know it's time to change out the stylus. Interestingly, Peter Ledermann has reported that my Zephyr stylus is x% worn and needs to be retipped, or not ... as the case may be. It would seem he has the right equipment, plus extensive experience to make such calls.
I guess that leaves me no better off than when I started this inquiry. Perhaps the 50x magnifier may have limited utility if it will tell me whether the sylus is badly chipped or worn. Other than that, perhaps the next best option is to run my #1 cartridge out for 1000 to 1500 hours, then send it to Peter Ledermann for a check. While #1 is out of commission, I'll use my #2 cartridge.
Other than that, I don't know what else to do. To wait for black vinyl shavings to peel off the records tracks to alert me that the stylus is shot is ridiculous.