> OSX is certainly a better choice for the pointy-pointy-clicky-clicky masses than windows by far. OSX is not, nor will it ever likely be made for serious hackers or sysadmins that actually care how things work at a low level
This is an extremely short-sighted, elitist point of view. Stuff like DTrace are absolutely fantastic and quite low-level, and applications like Instruments are quite helpful.
> like to
> choose their own window manager
Hmm that's 'low level' for sure.
> manage memory
OS memory management is incredibly tough. J. Random Hacker certainly has a hard time following LKML discussions on the subject, let alone diving into the code. echo'ing stuff in /proc/sys/vm/swappiness does not count as hackerdom on the subject.
> write/apply kernel patches to support new hardware
Nothing prevents you from writing kexts.
> run enterprise-level systems with rebootless kernel upgrades
I doubt the majority of linux servers are running Ksplice or kexec'ing into the new kernel. Your typical Debian install needs a reboot for the new kernel to be picked up.
> have low level file-system control/choices
I think HFS+ has done its time and needs to be phased out, and I would have loved for ZFS to not be acquired by Oracle. Still you can control journaled-ness and case sensitivity of HFS+ drives, which is nice. You can come up with whatever partition scheme you want since /etc/fstab is respected. Also, you can certainly implement/port all the filesystems you want, either 'natively' or through Fuse.
> get and apply same-day security patches
This is an area where the open crowd kicks ass. Many vulnerabilities though are not in the kernel or the base OS but in third party software, which can possibly run nicely on OSX and benefit from openness.
> have custom kernel-level security extensions that compile into every binary on the system
I'm not sure what you mean by that but if you have kernel security compiled in a userland program to be effective, you've got a problem.
> It is also certainly not for the wider range of users and developers that want an operating system they can install on their existing hardware that for most common tasks "just works"
This is true but ironically, I recently built a hackintosh on a Dell XPS 8300 which required much fewer hacks than Ubuntu to simply work. (Debian did not stand a chance as it would have been running half of Sid). Arch Linux fares better but needed quite some work to achieve a fully working environment. Yet in the end OS X is still a better fit for the machine.
> and/or want to easily manage all the software on their system with a mostly unbiased package repository system where everything is free, and where most of it can be legally modified.
Homebrew fits the bill. Also note how most of the Unix userland and a good part of the kernel is actually open [0].
So I assure you hackers can have plenty of fun poking around and living daily inside OS X.
[0] 10.7.3 kernel, http://www.opensource.apple.com/source/xnu/xnu-1699.24.23/