Krita's just lacking a OSX build. I've been using the windows build for a while. Krita's focus is on digital painting. I would say Krita is more comparable to Corel's Painter instead of Photoshop.
Krita is actually built on Qt libraries, just like VLC and even some of Photoshop. Which makes it look native on most platforms, and AFAIK won't require X11 on OS X -- because Qt uses Cocoa there.
The other workaround I can think of is to use Krita in VMPlayer(Fusion?) with Ubuntu. Sounds clunky but I'm doing that with the devel version of MyPaint . Wacom usb pass through on Virtualbox isn't working well.
