Many of the concerns raised were answered before but here they are in one place.
1) We already have our Accord/Camry; We purchased Acura TL to cover that part of the equation! We can rest that issue now.
2) S420 is not even on the same planet as Bi-Turbo or V12 or AMG drive train cars; My assumption is that the list of problems typically associated with "vanilla" S420 is going to be lot smaller than those stratospheric cars listed earlier.
3) I could not notice any rust; brake fluid looked clean; tires still had tread; they were matched Michelin Primacy set
3) Assuming air-matic suspension is already taken care of (aka already replaced with Arnott units) AND making sure all the options on this vehicle are actually working and a full PPI is done by a knowledgeable MB mechanic, the downside risk will be minimized
4) Yes; it has gadgets galore but if they are all working at this stage unless it has well-know problem areas associated with this car, I could take the calculated risk.
5) Obviously, this would be a leisure purchase financed by taking the money of out of my 401K (NOT!)
6) I would never buy a brand new MB regardless of our financial situation. For buying new, we always stay with "safe choices".
7) Even though I do very little mechanical wrenching myself, I know lot more and can pick up the knowledge via internet. As long as I have a trustworthy shop, I let them do the dirty work under my supervision and have no trouble paying the fair price for their services.
8) As pointed out before, with pirated DVDs and aftermarket scanners, getting the factory knowledge about diagnostics and repair is still relatively cheap
9) The biggest obstacle is to convince the boss! She would rather tell me to go and buy a new or CPO E-class at about three times the price of this specimen.