Save your money for the rear springs, I have a really fine set that have evenly sagged at least 40mm and I'll sell them to you cheap!
!
If you do lower the car using different springs, won't you have to use different shocks because the shocks are gas charged and help raise the car?
If no one in this forum can help you with your question about handling after lowering your car, then try the wheels & tires forum because there is a lot of info about lowering M-B's and using different wheels there.
Good Luck!
Tom