That looks like a very cool project, but the ease of use of XNA I fear, will divert people new to managed code away from SlimDX. As the guys from SlimDX themselves say...

SlimDX is, as the name implies, a slim and simplistic wrapper on top of DirectX. XNA, in contrast, provides a lot of higher level functionality that keeps you from having to deal with very low level details. Overall, this means that XNA is a fair bit easier to use, especially for newbies who are not comfortable with how DirectX works.
SlimDX is a great idea though.