Making a fading gif banner within Gimp is a true pain in the ass, im not 100% happy with the smoothness of this gif so it still needs a finishing touch:
Nearly all gif programs dont have a good fade transition effect and video edittors always tend to create a full colour background instead of transparant. This makes it verry hard for me to create a clean, proper looking gif except for one metod and that is manually create all the layers needed which is a pain.
After extended searching I came to the conclusion that using the easiest way was better after all. Simple frame switches: