By design, it's not a fully compliant ANSI C compiler, so it's never going to be complete, but it's complete enough to, for example, successfully compile Plan 9's driver for the Raspberry Pi USB controller with a minimal porting effort.
So, Dusk's compiler is not apple-to-apple comparable to the other, but comparable enough to give a ballpark idea that its code density compares very, very favorably.
It can be hard to tell how much extra complexity would be introduced by unimplemented features.