In addition to not interacting with the GNU toolchain at all (through MinGW), MSVC support will indeed enable native Windows debug info (as you mentioned) so native tools can be used to debug Rust code. Note that this isn't 100% implemented yet, but it's coming soon! Additionally you'll get interoperation with MSVC-compiled libraries. Libraries compiled with MinGW don't interoperate well with MSVC (and vice versa), so this enables Rust code to link against an MSVC-compiled native library.