* Static code analysis, profiling, and HLSL editing and debugging
* Multi-unit testing framework and refactoring support
* Third-party extensibility support
* Multi-unit testing framework and refactoring support
* Third-party extensibility support
The biggest roadblocks to .NET development/adoption are not toolchain related IMO, they are platform related. If you want to bring up a farm of windows boxes, you're gonna pay.
* Testing can be done through other tools such as Nunit.
* With VS2012, you get extensions developed by Microsoft, such as NuGet.