If you are aiming to write a multi-threaded application with some intensive non-graphics background threads as well as a Direct3D based presentation layer which of the two Visual Studio templates Core App or Blank App is likely to be the better choice.
Given that I'd rather not write my own button/controls it seems like Blank App with XAML and using a SwapChain panel would be the go.
However, the statement "...app directly implementing CoreApplication" intrigues me, what if any are the benefits of directly implementing CoreApplication?