I can't see why a conical profile would have any difference in life span versus other profiles. But they are any number of variables involved. Poor set-up, improper cleaning and care, dirty records, cheap stylus, etc. Any of these things will greatly reduce stylus life from the ideal.
My experience with stylus life, no matter the profile, is they last far longer than is commonly reported. Things do wear and change but the most important factor is has the stylus worn enough to cause permanent damage to the record?
Some people will tell you a stylus is shot at 1,000 hours or less. I routinely run my cartridges well beyond 1,000 hours with no damage to my vinyl. I keep my records and stylus clean but I am not fanatical on this point.
The best person to ask is the importer for Miyajima. A great guy, a wealth of knowledge concerning all things analog and he will give you the straight story. He is far more interested in a satisfied customer than selling a cartridge, or re-tipping, before it is required.