PC Games Hardware has a
technical interview on King Arthur II, for those interested in whether shader model 5 is better than the others:
2) In spite of the fact that for a Roleplaying Strategy Game visuals are not as important as for a shooter game why do you decide to utilize the very modern DX11 API?
The DirectX 10 and 11 versions have introduced only a handful of new, basic technics that cannot be utilized with DX9, basically they're full of structural improvements. The few features that are new and special in DX11 – like the tessellation support – cannot be used for the moment to build a game upon it, since it is still not wide-spread enough. However, the structural improvements of these newer versions can be utilized to run a more stable and faster game code compared to running only the DX9 on a 64bit Windows 7 for example.
More information.