I'd say we are dealing with so different cars that it is almost impossible to decide based on the potential service costs.
I'd compare the two listing what is relevant AND different.
In other words: knowing what I get with the S300.
Then estimate the delta in services maintenance.
Finally deciding if I want and CAN afford it.
In summary: find the price of the difference and decide if it is worth it.
Jorge
I'd say the C series are very likeable cars. But the S series is THE Mercedes Benz.
PS2: Also I'd say that if you quote de services with YOU either doing part of them or at least being the integrator and parts buyer you will reach enormously different figures.
Jorge