I know that some of GC members tried
Blender at least once. Here is a relatively new
Blender_addon/GIMP_plugin (released 2 mo ago)
allowing to paint 3D
Blender objects in UV/image mode using
GIMP. It's all being done in
real time with both
Blender and
GIMP running.
I've been testing it over this weekend and it works quite well.
P.S. when you click on the link it will offer you attachment download - don't worry, nothing's going to download on your computer, it will simply open
addon manual in your browser window.
Here's the
video link