I have had 2 SLKs over the last 6 years and the reliability has been perfect. I wouldn't have purchased a second one if I wasn't happy with the first car. I love the fact that it has a hard top and yet is a coup in the winter when we have a lot of snow and cold. I have had no mechanical problems with mine and although it is still under the CPO warranty until 6/13/09, the only thing that had to be repaired was the inside light. Even that did not cost me a penny. I love the car, the looks and the way it handles. I understand that the newer body style is a better handling car and will probably purchase a new one in about 16 months but for now I am very happy.
Lighter weight would obviously help acceleration and handling but I wouldn't want to give up the solid feeling