I am a C++ developper and i want to start to code in C#.
I don't know if i will use OpenTK or XNA.
I fear to have less utilities functions in OpenTK.
i have made a math library in C++ for OpenGL which is very close to D3DX and i don't have the knowledge in C# to convert it in optimized and clean C#.
If you are interested, you can use its source code to had more math functions to OpenTK (even if my code is not the best):
I hope it can help you in the OpenTK project.