Here is a comparison based on my experience
Antminer D3:
Specification advertised: 15 GHs +-5% , Power : 1200 watt
ACTUAL working specification: 17 GHs , Power 1000 watt :)
iBeLink DM11G:
Specification advertised: 11 GHs +-5%, Power : 810 watt
ACTUAL working specification: 10 GHs ...