I'll just say 1265 is a good start and a stepping stone to 1800mhz on HWbot/XS.
@zargana, the 8W difference in power consumption can easily be explained by the higher clock speed, which does in fact translate into better performance.
As everyone knows, Memory OC doesn't impact as much as GPU OC does.
HardwareHeaven tested both cards and the Sapphire at 1000/1450 loses to the Lightning at 1070/1400, with the latter of course having much better OC potential (see the 1800 MHz above.)
HH Sapphire dual-X
HH R7970 Lightning