All my works here were made with 3d max and/or photoshop on windows. It was a long time ago, thought. Now I'm trying to switch to blender/gimp/inkscape on linux and... well it's true that it's harder and it's more for programmers than for some regular designers, but you can definetly do the same stuff with open-source software that you do with the commercial ones. It's just a little bit harder.
You are welcome if you have any more questions on this topic