"Photoshop CS6 seems to run well under WINE on Linux"
Probably it works, but the question is how well it works? For example, there are issue with color calibration when using WINE? I mean, how well WINE APIs for color management work well with the Linux color management stack?
Another issue are printer drivers - if you need to print other color management needs enter the field - while you can usually trust the original drivers and profiles, not all printers makers release Linux drivers. When some features are handled by the driver (i.e.some B/W printing features in Canon and Epson printers, or Chroma Optimizer in Canon Pixma Pro/ImagePROGRAF printers), and some features may need printer specific applications. Wasting expensive A2 sheets it's pretty annoying.
In these situations, switching to Apple is a safer approach.