Is a good a idea to use a existent level editor?

Hi,

Is a good a idea to use a existent 3D world editor? I mean, find a level editor with Apache/BSD/MIT/Zlib, or some permissive license… and two communities helping one a another?

I found this:
sourceforge.net/projects/softpixeleditor/

I good idea? or what you propose?

Cheers,
John