Check out Genode.org, MINIX 3, or QNX. Seem to have gotten a lot more done than Hurd despite being microkernel-based OS's. KeyKOS is one of the best from back in the day with EROS being a nice x86 variant of it. Turaya Desktop is based on Perseus Framework.
Many working systems in production from timesharing to embedded to desktop that are microkernel-based. Hurd and Mach's problems are most likely due to design choices that created problems.
I don't know about the others, but at least both QNX and Minix3 cheated a little, i.e. allowing servers to write directly to other user space programs.
Also, the presence of microkernel+multiserver systems is still quite symbolic in comparison with the monolithic couterparts.
Many working systems in production from timesharing to embedded to desktop that are microkernel-based. Hurd and Mach's problems are most likely due to design choices that created problems.