W204 C-Class saloons, what should we know?

[8bit]

Looking at getting a new car to transport the wife and imminent baby around. She likes the look of the W204 generation C Class Sport models and there seems to be decent choice within budget. Core requirements are - petrol, automatic, 4/5-door, good boot size (for buggy and baby paraphernalia) and a wee bit of poke for when it's dad's turn to drive.

On the above basis we're thinking of a saloon in Sport trim with one of the V6 engines. Seems to be a fair difference in figures between the 2.5, 3.0 and 3.5, does it make that much difference in real terms? Also note from Wikipedia that there was a potential issue with those engines (http://en.wikipedia.org/wiki/Mercedes-Benz_M272_engine#Balance_Shaft_Gear_Issues), is that something that was fixed under recall or does any used car with one of those engines still have the potential for expensive work requirements?

Anything else we should know before we start looking like other issues, mechanical or practical? What are servicing costs and intervals like?

Thanks in advance