My recent experience with my early delivery '03 c32 (currently 80K miles) may help others:
1. under my extended warranty they replaced many parts while diagnosing a power loss problem, check engine light on problem and later an extended cranking period to start the car that occured in summer '08 (power loss was at first sporadic, and later chronic where the engine felt like a sewing machine):
replaced supercharger, supercharger pump, crank position sensor, both catalytic converters, valve cover gasket, injection valves....ultimate cause was "air intake intercooler had a minor leak, this in turn allowed coolant to accumulate on top of the valves...causing a delay in starting and misfire in the cylinder".
2. when no longer under warranty this past month, total power loss while stuck in traffic on highway where transmission was in drive but acted like it was in neutral (only warning was a high-pitched whine from the engine earlier that day): replaced tranny control unit (apparently a known problem, they did not charge for the part itself) and replaced dreaded veleo rad (a known problem, as everyone on forum knows by now). no charge for tranny control unit but the total for the labour and the rad was just short of $2k.....
I hope i'm correct in thinking that i basically have a new car now!!! i also hope this helps others!

 

what was the check engine light for?

so in summary, the shop threw a bunch of unrelated parts at the car in an attempt to fix it. then they claimed it was an intercooler leak and you were still having the problem.

 

my conclusion on the check engine light is that it related to the intercooler leak.....regarding the parts, your conclusion may be correct....i hope that's it for a while because i enjoy the car like the day i took delivery!! waiting for something else to tickle my fancy!!