I removed the quirks for my r9 270x and I have no stability issues whatsoever,
it's a really nice performance boost.

this is the line I commented out for my card:
{ PCI_VENDOR_ID_ATI, 0x6810, 0x174b, 0xe271, 85000, 90000 },

and here's full info on my system on this forum post:
https://www.phoronix.com/forums/forum/linux-graphics-x-org-drivers/amd-linux/937952-sapphire-dual-x-r9-270x-not-running-at-full-clock-speeds-amdgpu-and-radeon

let me know if you need any more testing on this, but I'm pretty sure it's
stable