XenServer 7.0 PCI GPU Passthrough Broken / Restarts Dom0

In XenServer 6,5 SP1, I had a Windows 7 x64 VM with a passthrough PCI GPU (NVIDIA Quadro 4000). Once updated to Xenserver 7.0, I added the following to /boot/grub/grub.cfg:

menuentry 'XenServer' {
...
module2 /boot/vmlinuz-3.10-xen root= ..... xen-pciback.hide=(8c:00.0)(8c:00.1)
...

These were known from lspci. I verified the correct PCI device setting still remained in the Windows VM.

The first time I attempted to start the VM dom0 resets (it restarts the machine); now, Windows just shows a yellow bang for the Quadro device.

I have set the priority as "major" because I am not the only one; a quick Google search results in many of the same issues (without any resolution): any production environment using PCI passthrough will be affected (it could arguably be a blocker). Similar to XSO-435, but on a production build (7.0).

Can provide logs (just show me how to get them!).