Another tweak I've wondered about is monitoring memory die temps. GDDR5 chips have internal thermal diodes similar to the GPU, and they can be enabled by setting a bit in mode register 7. Knowing the temperature of each memory die could provide useful diagnostic info for problems such as a heatsink not having good contact with the chip.
Yes! Mem temp management is critical to getting Vegas stable - I'm sure it would be hugely useful for stabilizing polaris as well. I now use a rule of thumb of core generally being about 10º cooler than mem, but clearly this is a very rough estimate, and depends significantly on heat sink design (or lack thereof.)
Also might give some sense of the 'asic quality' of the mem (if that's a thing...)