Maybe the Brits, Germans and South Africans get F30s with differently set-up suspension to the Aussies and Americans?

[I strongly doubt this of course.]
I have been bemused by the tales from across the Atlantic criticising F30s for "soft" handling. Sure, the car rides far better than before but this has not come at the expense of handling - even on base-model springs and shocks. People need to remember that the F30 is a big-ish car now - very nearly the size of an E39 - and it too has to appeal to a broad demographic. Equally, the new W205 is almost as big as the W124 - being slightly shorter but with a much bigger wheelbase. Look at the car's target market and it's clear that Mercedes Benz have tuned the suspension to appeal to a more mature audience on average. The way the new C-Class rides is entirely within Mercedes' discretion and not some result of how the car is intrinsically engineered. As always it's about the balancing act of compromise.
I don't know anyone in my circles, who is not in some way involved in motorsport or the industry in general, that drives a car like I do. Therefore I have no idea how the regular man on the street can claim that the F30 is "soft". By my experience a boggo F30 is no track burner - the adaptive suspension tidies things up for on-the-limit handling but I could hardly say that my F30 is scrappy... I personally think that body roll is really well contained for a car with such primary ride characteristics. The only bug-bear? Yip - sharp, high-frequency ridges and runflats. I'd expect that the M-Sport models would exhibit less heave but on the whole I take no exception to the ride/handling trade off on the 3er. And, neither does SA CAR mag who just voted the 3er top of its class in their annual Top 12 review, for that matter.
The C-Class will be more refined and will steer better than the 3er - I am also pretty certain of this given its more advanced front suspension layout and adjustable dampers available as standard. I am curious to see if and how BMW will counter this with the facelift of the F30.