I think your analysis of the situation is about right. I have acted for a number of dissatisfied purchasers of SL55 AMG cars (and other high end Mercs) and, frankly, it seems that their cars never get fixed. Eventually the dealer buys them back and offers a very good deal on a replacement.

I think there are two general rules. First, be suspicious of any car that has spent a lot of time in the workshop, especially repeated visits. And second, avoid cars with all of the high-end hi-tech extras, especially Keyless-Go and Distronic. I would not buy a 2003 car with Keyless-Go, it seems to have been an incompletely resolved installation at that time. While a pano-top is very desirable, I would look for a car without all the extras!

The best way to be sure is to speak to the previous owner.

__________________
JJ Rodger
2013 G350 Bluetec
1999 SL 500
1993 E300 diesel T
1990 190