VW Group is moving towards timing chains with their larger diesel engines. What you'll see is not at all like what you have with the older Benz chains. The systems are infinitely more complicated and require a huge amount of work to service. This is going to be the nature of the beast.

Personally, I'm a big fan of timing chains as long as they are reliable and easy to service. A lot of the VW guys prefer belts because they remember the chains on the VR6 engine that require a significant amount of labor around 120,000 miles. A lot of them are also very nervous about the future of the VW diesel engines (with 2, 3, or more timing chains on the back of the engine).

What it boils down to is that you can't beat the simplicity of the 70s and 80s Benz diesels. The same goes for the 80s and early 90s VW diesels. They run forever and can be repaired by most competent individuals. The future is looking bleak in that respect... both VW and MB engines require special tools, special computers, and specialized knowledge to diagnose and repair them.

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2012 Volkswagen Passat TDI - 103,000 miles
2004 Volkswagen Touareg V10 TDI - 160,000 miles
2003 Ford F-350 PowerStroke 6.0 -- sold
1987 Mercedes-Benz 300SDL -- 307,500 miles -- Retired
1991 VW Jetta GL ECOdiesel -- 429,531 miles -- RIP
2000 Volkswagen New Beetle TDI -- RIP
1987 Mercedes-Benz 190D 2.5 Turbo -- sold