Supporting GDC toolchains will allow VisualD access to a better compiler, and also to cross compilers for other architectures.
VisualD should also support the 'Platform' selector, potentially allowing configuration of a desired toolchain for each platform.
I would like to use an ARM build of GDC when the Android platform is selected, or a PowerPC toolchain when XBox is selected.
As with VisualStudio?, it should be possible to support multiple platforms (with potentially different compile options) within the one project/solution.