The C36 or C43 AMG will be a lot quicker and sportier, and they look great too, no doubt about it.
But the car you already have, while it's no corner carver like the one you might want to replace it with, is a REALLY durable long distance cruiser, easier to maintain, with less computer gremlins to sweat, and very low mileage, for that model, and when you consider the miles left in it.
You should have no problem selling the car if it is priced reasonably, and is in good shape. It's a VERY good car, about 80% of what you'd get in an E500, the E class supercar of the time. Think VERY carefully before get rid of the car.
Even with 110k on the clock, there is a real good chance in the long haul, ie, over the next 10-20 years, it will outlast the C36 or C43 and have been less costly to run over those years.
But the C36 and C43 are good sedans too, they look good, and could NEVER be called boring, they are real sports sedans, and a definate alternative to the M class BMW 3 or 5 series. If you are willing to pay the higher repair costs and risk the possibility that your car will have worse build quality and computer gremlins, then the change could be worth it.