>They all had problems with very sporadic hard crashes

I had such an issue recently, on a laptop with an Intel igpu and an Nvidia primus card.

I'm not a coward, so I debugged the system, and found that the crash was caused by the Intel i915 driver trying to do some tricky hdmi related mumbo jumbo with the hdmi port that wasn't even connected to the igpu, it was connected to the nvidia gpu.

When I contacted intel bugtracker, they just said "ah, Nvidia... well, even though their kernel module is open, it's not on the mainline kernel, so go fsck.ext2fs yourself".