I'm pretty sure the CDI will not be as reliable as a W123, looks are a rather subjective issue but I think the W211 chassis looks great and it will stand the test of time, just as the W123 has.

I really think you need to drive a W211 CDI before you pass final judgement but it would be hard for me to imagine anybody thinking a W123 would be preferable to a CDI unless the ONLY consideration is reliability/fixability.

I'd take a CDI in a second if I was in the market for a 50K new car.