Hold on everybody, there are two things to try:
1. On page 4 of this thread DigitalAir has offered his solution. Check it out.
Probably a no-go for the majority of You (including me), but I went for a dual boot option with Windows 10. I did in order to use the full capability of Excel.
Now, here are some thoughts:
+ Win 10 looks and feels quite good
+ It does a lot of the things which El Capitan offers
+ With a tweek (Trackpad++) even the trackpad works very similar to the original experience under El Capitan.
Now I must admit, after already used with Mac OS, I wouldn't completely migrate to Windows. Mac OS is still feels and works more even across different apps and does offer a slightly better experience because of the integration.
Yet my message is: Windows 10 has reworked all the short comings from the previous version and works decently. While it is still a hard sale for anybody working with Mac, it is a real alternative. I certainly hope Apple would take notice and rethink the way of improving Mac OS, as Windows isn't lagging too far behind any more.
I'm using rMBP 13, mid. 2014, 2,6Ghz, 8gb RAM