It took a little experimenting but I can confirm the above. Performance seems okay at 1600x1200, High (using a GTX 460)

Additionally, I had audio issues but was able to resolve them. Here's the full story for background:

winecfg audio was set to Emulation and 44100 (for another app). Had no audio from Witcher 2. Set to 48000 and I got audio but only for a minute or so. Disabling pulseaudio is what did it in the end. Changing the audio output quality was unimportant.

tldr; If you have sound issues disable pulseaudio and fall back to ALSA.

Anyone tried The Witcher 2 using CrossOver Games on Mac?

I heard The Witcher 1 works that way, though I have doubts about 2.. Would love to buy this game but don't want to spend money if I can't play it on my mac :(

That's a misconception. WINE doesn't emulate directx calls it just intercepts and attempts to map them to a similar opengl function or functions. (Which is pretty much how MGE for Morrowind works to get better graphics and graphic related capabilities...)

I briefly considered attempting to run it under Ubuntu 10.04 x86-64 + WINE but I just don't have 23GB of freeable space ATM plus I really didn't want to waste the time getting it running so I just installed it to my Vista 32b partition.

Most of the time games that do run under wine run almost as fast as native windows. Some even run better under wine but most are a bit slower and many require tweaking to get going...

The other big thing is to avoid using Microsoft's .NET framework. WINE can emulate some of .NET but not all. In general, a program that's compatible with older versions of MS stuff will have an easier time in WINE, just because it takes time for the WINE devs to catch up.

can't run on mac because there's only one mouse button.

You can connect a two-button mouse to a Mac via the USB.

Wow, what a noobie. Your argument has been rebated. Besides that the point is that of marketshare. Not hardware.

I'm just shocked that the dev team doesn't optimise the game for wine usage, they would easily get more profit by including both linux and mac users .....

FWIW, this is no longer true since many years. Standard apple mice have configurable up to 4 buttons. Personally, for Gaming I still don't like em much.

Since playng on a Mac came up, I am playing on a Mac Pro under Boot Camp Vista and this game needs native Windows/DirectX.

That being said, it runs absolutely fine. Had no performance related problems pre-patch and I do not have any problems now.

If everyone keeps whining maybe it'll happen, its coming on Xbox and PS3 isn't it?

They should change its name to that: Whine ^3.
Anyways, there are some rumors in the industry that devs want to ditch DirectX and go back to a direct to metal programming mode. If that happens, you may see that Whine, I mean Wine becomes irrelevant. Therefore, you could run it on any platform.
I wonder how many of the Whine supporters are actual Software Developers or have an idea of the costs to do such things. I've worked with linux for years and something that strikes me about the linux community is its disconnection to reality in some aspects of software development.

Linux is such an infinitely small market and yet Linux users still expect to be catered to. Truly weird.

Totally agree with you.

Now,

1. where did you hear those rumors.

2. The fact that they stop using directX does not mean the software can be run on any platform. Granted it greatly reduces the work of porting it, but the binaries still need to be modified.

Go to HardOcp.com and look at the news from 1 to 2 months ago. It was an Interview with ATi VicePresident.

Caution there. The IT pros (the hard core, not MS-only noobies) would disagree. For security, email and fileserver and webserver markets recheck your data. And retail users for Linux (SUSE, Redhat, ubuntu and Debian) are WAY up. Never underestimate the "underdog" They have a way of breathing down your neck when you least expect it. Remember your Android phone? what do you think you are running on that thing anyway...oh the Mac OS is a BSD derivite, which came from Unix and Linux developers. If we took away BSD, Redhat, CentOS, Debian and Apache you wouldn't have half the security products or routers you have now, and your webservers would be hacked every other day. Want proof, put an IIS server up without a security hardware appliance (which virtually all of use linux) leave it naked on a Rogers (or equivalent in your country) network and see what happens. Did that by mistake on a Univeristy student website for short term project I setup on their personal machine via DynDNS as a quick favor (I was not a student) for a group project (friend+group had no clue) and forgot about it. Somone killed their OS remotely!! (fortunately I could recover their data).