This is not to say that CS2 is necessarily superior to the GIMP; it may or may not be. It doesn't really matter;
Oh god no. As someone who has used every image editor under the sun, a good image editor _does matter_. It has a direct impact on how productive you are.I love open source. I really do, but GIMP is one of the most horrid applications I've used. Not just graphics applications. All applications.
GIMP is anti-user. You to get frustrated doing simple things, and expect to spend more time on Google than GIMP. And not in the good blender way where you learn a new shortcut and you become more productive. The "oh I'd never expect to see that option there" way. Even something simple as basic window management is a pain in the ass.
MyPaint, .NetPaint, and Inkscape make GIMP look like a joke. I hope the unusable mess that is GIMP either dies or gets it shit together.