What is it the wears out on a cartridge?

Line-contact or micro-ridge styli will last longer than conical or elliptical styli; because the former develop less friction (even though most cartridges that use them require higher VTF)

In theory, yes. In practice, only if the alignment is correct to reduce the stress (contact force/unit area) on the groove walls.

All very true. And for the easiest way to set the stylus rake angle (SRA) and other delights, read this thread:
http://forum.audiogon.com/cgi-bin/fr.pl?eanlg&1140840022&openmine&Nsgarch&4&5&st0

BTW: VTA (both as an idea and as a number) is a useless concept and impossible to achieve, because:
1. No cartridge in existance has physical properties that would exactly match a given cutter head (which it would have to do to even THINK about setting VTA).
2. Cutter heads are different from each other anyway, and
3. Even if a cartridge matched (at least) one cutter head, and COULD be so adjusted, you'd still have to set the SRA to get the stylus to lock into the groove properly; and doing so would throw off your VTA adjustment anyhow!

So anyone who discusses VTA as being an important parameter (people like Mikey Framer) is a charlatan who knows nothing about physics or mechanics! So there ;-)
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Nsgarch wrote:

Line-contact or micro-ridge styli will last longer than conical or elliptical styli; because the former develop less friction (even though most cartridges that use them require higher VTF)

In theory, yes. In practice, only if the alignment is correct to reduce the stress (contact force/unit area) on the groove walls. Correct alignment also is known to increase separation, and reduce phase errors, crosstalk, and distortion :o)

Does Benz have tubular cantilevers??? L2 in particular?? I just got a stylus cleaning kit for Christmas.

Modern suspensions use space-age polymers that won't exhibit deterioration for a few decades. In addition to that, their properties remain consistent over a large range of temp and humidity.

Line-contact or micro-ridge styli will last longer than conical or elliptical styli; because the former develop less friction (even though most cartridges that use them require higher VTF)

Keep your records clean. You don't HAVE to be a fanatic, but if you're NOT, then you'll wear out your ears faster than your stylus!

Don't use liquid stylus cleaners. First, they don't work. And second, if your cartridge has a tubular cantilever, the liquid could capillary up the tube and dissolve the suspension. Do use the Onzo Zero-Dust before every side (more for your ears than your stylus.) Every half dozen records or so, clean the stylus with a Mr. Clean Magic Eraser device you have to make yourself (it's easy) For more info on the ME, do a forum search. But the ME is the ONLY thing that will clean your stylus sparkling new -- including the crud that builds up between the back of the diamond and the bottom of the cantilever. Follow with the Onzo to remove any loose debris.
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I have read that whatever surrounds cantilivers will dry out and deteriorate with time and the cantiliver can actually fall out.

The diamond tip will probably last for decades and enormous hours but cantilever and suspension will loose flexibility hence substantially degrading performance

I've heard that local climate impacts the rubber O-ring at the base of the cantilever - hot and dry causing it to become brittle more quickly.

One thing I would like to know. Do some suspensions on some brands last more than others???

Jan Allaerts uses 120 old rubber for the suspension on his cartridges to avoid aging of the suspension.

This is what I know. Your diamond lasts due to use. Your cantilever lasts due to time. Keep your records pristine clean. Clean your stylus every listening session. Also Last stylus treatment could be used, however some manufacturers advise against it on the grounds some of the treatment could damage the glue or some other adhesion in the cantilever. Tracking weight is crucial. Too much and the diamond will wear sooner or too little and the stylus will bump up and down potentially causing even more wear. At least on your records. The suspension does have a expiration date but it is not stamped on your box. The sound will change over time. One thing I would like to know. Do some suspensions on some brands last more than others???