I thought about chip-tuning my E300's but have heard so many bad experiences of reliability with people tuning their cars in general. What can go wrong and what's the chance? Don't think I'd ever take a chance on knocking the reliability off my cars. They startup every time i need them to without a hiccup.

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Only diesels in this driveway.
2005 E320 CDI 243k Black/Black
2008 Chevy 3500HD Duramax 340k
2004 Chevy 2500HD Duramax 220k

Because of were you live, you should head over to Rocketchip....Jeff is in Red Lion, PA. There's really no risk with someone of his caliber...of course there are a number of good tuners out there.

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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 159k miles
06 E320 CDI "Rutherford", Black on Tan, 179k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 145k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 77k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

If you're perfectly happy with how the car is stock, then cool, I completely understand the hesitation. For some of us, we want something more. Sometime more than what the manufacturer decided they had to do to comply with EPA regs & CAFE fuel standards. There's never a sure-fire method for finding a good tuner - everybody has SOMEBODY thats been upset. But factory stock DME's or engines et al fail on the rare occasion as well. For me, it's a trivial issue. Do my research & due diligence, find somebody who's been in the business a long time with a prove track record, and start asking them questions. If they respond with logical answers that make sense, then ya - to me, it's worth that risk. If I feel they're blowing smoke or won't tell me anything at all - I'll pass along to the next.

In short - it all depends on what you want out of the car, and your assessment of risk. if you're modding the car at all - a good ECU tune is pretty low on the list as far as risk to the long term life of the car goes.