Linux user myself! I cheat though, I run CS4 in an XP virtual machine, and the XP system works better virtually in Linux than the actual hard drive installed version I have on my other partition. Go figure.
Are you using the latest unstable Darktable build? It's amazing, and very different from the stable release. I saw some videos of the mask selection tool they are working on. In my opinion, this one program could be enough to get more photographers to switch to Linux. Hands down the most professional image program I've been able to find for Linux. When the Gimp finally gets 16 bit support and non-destructive editing, I'm really not sure if I'll stick with Adobe or not.