I do production, and I manage the IT of a multi-platform marketing communications company, so I feel I need to add my experience to this.
No, we don't us X in the graphics/production area yet, but we've been running OS X server since it was still based on the NeXT GUI. It hasn't crashed for three years running.
Under 9 Quark runs OK, but with certain situations is highly unstable and sadly even undependable. Frankly I've been unimpressed with Quark overall because it costs a great deal and only with version five did Quark actually start using the Mac OS window defs that were introduced in OS 8!
Quark is almost a metaphor for what OS 9 is going to suffer from if Apple keeps patching it: unscalable code as the world moves to 64-bit processing and multi-processor computing.
OS X suffers from having little documentation or track record, but developers have been keen and quick to learn that porting clean code to X isn't so bad.
As to crashing, rebooting 9 is a cumbersome process. I run X %90 of the time at home where I do graphic design and web development and I hammer my G4 500 MP and it's never crashed. Apps will crash, but rerunning them is better than restarting when you have several processes running at once. I can copy, burn, rip files and still type without a hiccup. Doing batch jobs in 9 ties up my machine even if all I want to do is check a web page or write an email. Basically it makes one computer more useful. You should save often, regardless of OS or platform, the work you lose from apps crashing is always a risk no matter what. So why not save the hassle of rebooting and getting back to where you left off? Rebooting inhibits creative flow more than anything else I can think of.
No, I don't think OS X is a prime time OS right now, but it will be. I've run it since beta and watched the development skyrocket. I can already do things OS 9 never did so really we're looking at a whole new land of developer opportunities.
OS development is a huge amount of work, especially at stages of transition like the one Apple is doing now. Still I'm very appreciative of the speed of improvement 10 has gone through.
When I upgraded to a Radeon video card 10 got better, then ATI started doing monthly driver updates and most of those up the 2D a bit. There are tricks to speed X up too, but the GUI creates a *perceptual* speed issue. Disk access, file copies and other I/O operations are at least 1/3rd faster on the same hardware from what I've seen — they just seem slow. The foundation is there, The GUI is catching up. So I think that old hat *NIX folks and techies are fine with 10 but Apple can only move forward or they won't be able to sustain themselves. Basically after adjusting to all of the changes I've been able to work better and look forward to 10.2 (which *is* impressive when you see a beta in action).
Looking at Google, most of the Windows users are still using Windows 98! Windows 2000 is substantially improved from 98, yet a huge slice of the pie is still using older versions and now MS is pushing XP as hard or harder than Apple pushes OS X (you must buy a recent computer to run it, etc.). It's not that different, just a larger slice of the pie.
Just had to say all that. Really I feel that every point is valid here, it's about what you do and what works for you, and as such obsolescence is not something that should get in the way of what you do. OS X will get there. It has more options and expansion in it's source code than OS 9, but the painful transition must happen.