Ironic, I'm pretty much cross shopping B6 S4s and 05-06 MCSs for myself recently but have been slowly talking myself in to the MCS thanks to poor mpg in the S4. Looking forwards to seeing the photos. Good luck with the sale!
Per Audi, there is no scheduled timing chain service. The chains make zero noise at startup and the oil has been changed religiously every 3500 miles with synthetic so there shouldn't be anything to worry about with my car.
If you would like to have a PPI done, feel free to contact me.