Not sure how hardcore I am, but I would definitely consider myself a "linux type". I take your point about the lack of a decent package management system. I run Debian on my ThinkPad so I know what a good package management system looks like. I also take your point about Macs being a more closed system.
But for me, being a web developer who doesn't do much in the way of kernel hacking or other deeper system type work, OS X really is effectively Linux (or Unix as the case may be) with a more polished interface. I would never have considered getting a Mac if OS X was not based on Unix.
I am much happier with a combination of OS X on my desktop (used for work plus multimedia entertainment) and Debian on my laptop (used for work) than I was with Windows on my desktop and Debian on my laptop.
The problem for me is that OSX isn't linux. As a power user, I do some pretty in-depth stuff that requires the proc file system. Not only that but Mac drivers behave differently than linux ones in terms of the Unix philosophy. And Mac doesn't support more hardware than Linux even though it's a commercial operating system.
Example: I have a Hauppage HVR 1600 TV tuner with on board MPEG-TS transcoder. What linux allows me to do using the character device /dev/video0 either through netcat or through SSH stream the device across the network to another computer, effectively creating an MPEG stream of live TV. I can change channels using V4L2 architecture.
Thus when I'm in college my friends can record shows through my computer through the network onto their laptops (obviously the same channel at a time) simply by tapping the stream.
And because Mac doesn't have a great package management system you probably spend more time than you should upgrading libraries you use (depending on your setup obviously, I've never used Rails so I don't know what goes into that but PHP could be a bear).
Personally I like the expose feature of Mac and I was upset that it took either retarded compiz or a half broken hack to get it working on Linux. Then kwin came along, which does all of what finder does and more. And I will give Mac props for inventing that because it's one of the most useful window management techniques (I find taskbars outdated), but when I look at their system I can see that while I get stable polish, I get overall less features, turning it off, then turning it on kills plasma rendering properly).
But in terms of raw features that are really nice and extensible albeit crashy, commercial OSes, Mac included are always behind. (I mean seriously no one has addressed dependencies and dynamic library management like Linux has.)
I completely understand where you're coming from and totally agree that for the kind of stuff you're talking about, Linux is the definitely the go.
Open source web dev tools are great on the Mac though. I get by just fine using Ruby Gems for all my Ruby/Rails package management needs (the Ruby Gems system actually makes sense on OS X where as on Debian, it just felt redundant at best and annoying at worst) and I prefer to compile Ruby, MySQL, PHP, Git etc. myself in /usr/local anyway. I feel like I've got more control of where everything goes that way. When it comes to using these kinds of open source tools, I very much prefer to have a Unix style terminal to work in rather than what passes for a terminal in Windows.
I'll never totally give up Debian for OS X, but if it's a choice between Windows and OS X for my general work/entertainment machine, I'll choose OS X.
But for me, being a web developer who doesn't do much in the way of kernel hacking or other deeper system type work, OS X really is effectively Linux (or Unix as the case may be) with a more polished interface. I would never have considered getting a Mac if OS X was not based on Unix.
I am much happier with a combination of OS X on my desktop (used for work plus multimedia entertainment) and Debian on my laptop (used for work) than I was with Windows on my desktop and Debian on my laptop.