Rice Hauler here,
I own a 2000 E55. It is my daily driver and I can tell you it's a great car. I have approx 78,000 miles on it and the car has performed flawlessly.
Someone had mentioned the M5 as an alternative. I have a close friend that has one and it too is a terriffic car. Very Sport oriented. but I always remind him that when we show up at a club together they always park me first.
I also have the ML55 and have had that further modified by Hartmut Feyhl at RennTech. Engine intake and fuel injection upgrade along with Headers and Exhaust work. Good for another 60 hp and 60lbs of torque. They Also dropped the suspension 2.5in and added 19in wheelsStiffer adjustable Koni shocks and heavier duty sway bars. The guys that run my shop for me really like it and It runs great but the build quality is not up to the rest of the MB line.
The AMG line for MB has been a nice addition to the overall line and the strength of it is that 5.5liter engine. The flexible service system works and is amazing at how it calculates the service interval. No more remembering when to service the car.
My only caveat is that my girlfriend usually drives this car When she is not in our SL 600 AMG, and after a week of her driving the "intelligent engine/transmission" relearns her driving style which is best summarized by the movie "Driving Miss Daisy" so for the first100 miles or so all my shifts are off etc.
If you can find one and the service records check out go for it. Where else are you going to get Corvette/Porsche performance and 4 doors.
Hope everything works out for you.