Injora Fat Viper VS. GoupRC brushless motor and transmission compression.

I love my injora fat viper, but a commenter recommend the GoupRC motor so I gave it a try. They both work, the GoupRC is cool, its cheaper, its faster actually (perhaps the purple viper would be a closer comparison?) But the injora is tighter, smother, has more torque, and generally feels higher quality.... but is it worth the extra money?