I am back on track after a smooth clean install, and out of happiness i installed Antergos on 3 partitions with different DE.
Also to test the multiple display support, because with Gnome it’s very bad.
My next challenge to get working on a MacBook Pro with Optimus Intel + NVIDIA GeForce GT 650M GPU’s.

My setup now: 4x boot on a MBP, same computer, cables and displays:
1 MacOS ElCapitan -> multiple displays working out of the box
2 Antergos Gnome -> even dual display isn’t working properly
—> interface fonts are pixellated, screen dimensions are wrong, sometimes and sure after a connected boot all displays freeze on a black screen, …
3 Antergos OpenBox -> dual display working after some tweaks (RandR)
4 Antergos XFCE -> wow never seen a better multiple display support (RandR), but don’t like the DE interface.

But i like Gnome, so:

My questions:
Can somebody explain me why multiple displays aren’t working properly with Gnome?
Does somebody know how to get multiple displays working properly with Gnome?
Can i install and use without any other major problems the display packages (RandR) and settings from XFCE in Gnome?

Also tried to install Bumblebee but this messed all system up and was the main reason for the clean reinstall.
But this i will discuss in another post.