"ReactOS should be seen as something more like GNU Hurd. An exercise in kernel development and reverse engineering, a project that clearly requires a high level of technical skill, but long past the window of opportunity for actual adoption."

I understand your angle, or rather the attempt of fitting them in the same picture, somehow. However, the differences between them far surpass the similarities. There was no meaningful user-base for Unix/Hurd so to speak of compared to NT kernel. There's no real basis to assert the "kernel development" argument for both, as one was indeed a research project whereas the other one is just clean room engineering march towards replicating an existing kernel. What ReactOS needs to succeed is to become more stable and complete (on the whole, not just the kernel). Once it will be able to do that, covering the later Windows capabilities will be just a nice-to-have thing. Considering all the criticism that current version of Windows receives, switching to a stable and functional ReactOS, at least for individual use, becomes a no-brainer. Comparatively, there's nothing similar that Hurd kernel can do to get to where Linux is now.

I'd still consider them more similar than not.

Hurd was not a research project initially. It was a project to develop an actual, usable kernel for the GNU system, and it was supposed to be a free, copyleft replacement for the Unix kernel. ReactOS was similarly a project to make a usable and useful NT-compatible kernel, also as a free and copyleft replacement.

The key difference is that Hurd was not beholden to a particular architecture, it was free to do most things its own way as long as POSIX compatibility was achieved. ReactOS is more rigid in that it aims for compatibility with the NT implementation, including bugs, quirks and all, instead of a standard.

Both are long irrelevant to their original goals. Hurd because Linux is the dominant free Unix-like kernel (with the BSD kernel a distant second), ReactOS because the kernel it targets became a retrocomputing thing before ReactOS could reach a beta stage. And in the case of ReactOS, the secondary "whole system" goal is also irrelevant now because dozens of modern Linux distributions provide a better desktop experience than Windows 2000. Hell, Haiku is a better desktop experience.

> There was no meaningful user-base for Unix/Hurd so to speak of compared to NT kernel.

Sure, but that userbase also already has a way of using the NT kernel: Windows. The point is that both Hurd and ReactOS are trying to solve an interesting technical problem but lack any real reason to use rather than their alternatives that solve enough of the practical problems for most users.