Any advice on which of the 2 to purchase. Basically they both are around the same mileage and same price. Do any of the 2 have a poor reliability record? I am really loving the S600, but have concerns of hi cost maintenance to the 12 cyl .. I do not know the history of either model. would greatly appreciate any advice from you Mercedes enthusiasts with knowlege as I am a newbie with no prior knowledge with MBs! I am ready to learn.