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Back in the old days, they used to say timing chains were better, but that was a different era where belts usually needed replacing every 20-30,000 miles, while a chain was good for the "life of the car". That was also an era where "life of the car" usually meant it was junked by around 100,000 miles.
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My purely anecdotal response to this: our first new car purchase was a toyota minivan with timing chain in '92. "Life of the car" was 360,000 miles and chain never posed a problem. (Quick/cursory look around the web is that this is not an anomaly for well-serviced toyota, but....)
Now, if just one more poster has a similar anecdote, we'll have data!
P.S.--your post will lead me to some discussions with a couple of mechanics I know, so thanks!