To awsner your questions.
Yes, we have the VEGA 56 hashing Ethereum at the same rate as the VEGA 64. Just took some tweaking. but its using the same/similar power and the same hashrate
ETH hashing with AMD cards basically comes down to temp and memory.
At the most energy efficient rates (38-40 MH/s @ 150-175W), we are able to get the VEGA 56 to the same levels as the VEGA 64.
We are unable to get the VEGA 56 to reach the peak hashing levels of the VEGA 64 (43-45 MH/s). so right now, at what seems to be the msot efficient rates, he cards perform the same. that may change however:
-with larger DAGs/difficulty the 64 may start to chart up over the 56
-with new drivers and suppor from both amd and he mining pools he 64’s higher memory clock speed may start to gain an advantage.