These days you're better off with Minix 3. It's documented much better, with a book to boot, it's a much better microkernel than Mach, and it has a lot of activity around it.
Though I agree the Minix 3 microkernel is more elegant than GNU Mach, the Debian GNU/Hurd distribution has >80% of the package base building and largely running, which means it has a higher software selection.
The Hurd's documentation is pretty good for a project of limited manpower, just scattered.
Because strictly speaking the Hurd is only the userland servers, there's plenty of opportunities to work on porting and hacking them. The Debian GNU/Hurd might get USB and sound soon with NetBSD's rump kernel drivers phasing out the DDE framework in Mach, for instance.
Minix is basically ABI compatible with NetBSD, so going from a Debian/kNetBSD port to Minix would be easy. There was one once, way back https://www.debian.org/ports/netbsd/ but its dead.
This is not remotely true, and it sort of gives away an ignorance of either project. (I'm actually fairly ignorant of Hurd myself, but I'm familiar enough with MINIX to know that the comments about it are pretty far off target...)
I also find it odd that you specifically mention MINIX's documentation, because it's arguably the weakest point of the whole project. Even as for the book, if someone thinks they're going to be able to pick up the latest edition of Operating Systems: Design and Implementation in search of documentation for either MINIX-the-project or MINIX-the-software, they will be sorely disappointed. The fact that the book is now about a decade out of date is one reason for the latter. There are a number of reasons for the former.
Again, I can't imagine that anyone with a current, even-cursory-level understanding of MINIX would hold the requisite opinions to make the comments that you've left here.
