Because the original ETM was contact based and wore itself out, I would suspect that a lot of the differences in 'mileage before failure' are based on driving style. In other words, the more the gas pedal is used in different positions, the longer the life.

Remember, most casual driving is between 1500-2000 rpm for best MPG, and a lot of idle speed will wear out that position also.

I understand your concern. Usually, when the ETM fails, it does so in a progressive nature. You will feel it as it no longer wants to hold a certain rpm or gets messy at idle. By the time the check engine light comes on, it will be time to park the car. Make sure your AAA membership is up to date if you want to find out how long the ETM will last.
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