I assume your talking about the newer mini starter? All I can say is, I just replaced the original (mini starter) on my '96 Dakota a couple months ago after 170,000 miles of use. It was doing the exact same thing as your's was. When I took it apart out of curiosity, the only thing wrong with it was the solenoid contacts were all but non-existent. Everything else from the bushings to the brushes looked darn near brand new yet.

I originally had a stock replacement type mini starter from 440 Source on my 500 ci Aspen (now on the Dakota) and it worked fine except,,,,,,,,,,,hot soak restart. The headers are very close and it didn't like the heat. Shut it off hot, come back 10 minutes later and it sounded like you were trying to crank a 20:1 5,000 ci engine over. Replaced it with a Powermaster XS Torque and problem solved. On a stock vehicle, especially a S6, the starter (provided it's not some cheapo Chinese knock off) will probably outlast the car.

I'm not sure if the new type starter actually spins the engine faster or it just sounds like they do. The old big Chrysler starters, aside from 426 Hemi, were gear reduction also from at least as far back as 1962.

I'm an auto tech and the only time I remember replacing one of the starters is on high mileage vehicles, meaning over 150K and then, very seldom. They seem to be good starters.