S500 W221 ABC Reliability, etc

[ian_uk1975]

Thinking of getting a W221 S500 (06 or 07), but am a bit concerned about reliability with all the technology crammed into these cars. Of particular concern is the ABC system as I know this has a terrible reputation on the SL500/55. Is the ABC system on the W221 just as unreliable? What should I look for when buying that could indicate problems with the ABC system? If I get scared away from an S500, my next choice would be an Audi A8 4.2 TDI, which seem to have a great reputation for reliability (but the S500 has more toys).

Thanks.