I have some issues with two different laptops, one with an Intel/Nvidia combo and one with an Intel/Radeon combo. Although not strictly related to have a gdm login on Wayland I think it's worth describing.
Intel/Nvidia (binary driver):
The Nvidia one (intel + nvidia blob) is working perfectly with Fedora 21 but not on Fedora 22 with the "Optimus offloading configuration" as depicted in Nvidia's README [1]. The X server simply crashes, and there is no way to have a GDM login screen with this method. I was using the X configuration file described in the docs plus the script /etc/gdm/Init/:0 for running the xrandr commands at login. Also, glamor is loaded even though its loading is explicitly disabled in xorg.conf.
Unfortunately the laptop can only work with such configuration, the included GTX 860m does not work with nouveau reliably (lot of console errors and some crashes, no 3d) and there's no way to disable one of the cards through the bios.
I've tried updating xorg with some 1.18 patches [2], removing glamor,
forcing root access for everybody in Xwrapper.config to no avail, I
always got the same crash. I'm considering this a regression... should I open a bug or it will be simply closed because there is the Nvidia binary involved?
Intel/Nouveau and Intel/Radeon:
When using wayland, there's no way to use the second card (DRI_PRIME), it will simply use the first card for GL programs or crash directly (nothing useful in the logs). Is prime supported on Wayland? The server is also always started as root, wasn't it supposed to start inside a user session by default on Open KMS drivers?