My best Samsung timings still do 33MH/s+ on my 580, so I would think so.
And this is the one that cost 0.15 BTC correct?

Not selling those atm, of course.
I'm curious at what voltages GDDR5 chips REALLY work...Hynix datasheets
mention 1.35, 1.5 and 1.55V, yet I see 0.8-1.1 range everywhere (wattman, GPU-Z,
hwinfo...)
This is the memory controller you are seeing afaik.
...and that means what? Memory voltage is memory controller voltage + some other voltage?
No, memory voltage is COMPLETELY different from controller voltage.