I don’t think I’m saying anything new here, but if the free software is superior, then it’s easier to make the argument to try it out. If it just has similar functionality, then there’s little incentive to move over. A good example is GIMP being presented as an alternative to Photoshop. It’s not. Not even close. And I hate Adobe and refuse to pay for their crap. Even price isn’t enough. If your job/business depends on a piece of software that cost a lot of moolah Vs. an unknown free application, the free software loses. So you need a superior application plus an easy way to migrate all your data.
Krita rocks! It's amazing if you're a freehand artist. I think the brush engine is better than PS. Krita is also fast and can handle large images with multiple layers with no problems.
Also, superior depends on the user and use case. One person might find that GIMP has all the tools they actually use in Photoshop, and another might find that the ones they use are missing from GIMP. Without knowing the audience, it's hard to know what they want to hear.
As someone who does not do any sort of professional photo editing, I find GIMP and Photoshop to be equally confusing as hell. The only photo editor I've used with any degree of success is paint dot net, which obviously doesn't have the same firepower as the bigger options.
Thanks for reminding me that Pinta exists. :D I remember not enjoying it as much as paint dot net, but I'm a dirty Linux user so if I ever need to do some photo work I might give it a shot instead of fumbling around on GIMP forever.