At a train club I belonged to, MANY cars with Kadee wheels (mostly in
non-Kadee sideframes) wore down the ends of the axles to a round nub!
In a high-use context, metal axles last longer. Also sintered wheels
like Kadee etc seem to pick up crud more easily -- we sometimes had to
scrape a layer of stuff from the wheel treads with an X-Acto blade!
If we didn't do that, the wheels would redeposit the crud on the track.

But yeah, on a private low-mileage layout, it's probably not an issue.

I'm waiting for Kadee .088 equipped trucks before I buy any more. No
way I'm paying for wheels twice anymore.

Tim O'Connor