2011 Vitali would have been a more difficult fight for Haye because he wouldn't have feared to chase him around the ring and he trows much more punches as his younger brother. But I do expect Haye would have looked better against him because there had probably be more exchanges and he wouldn't have dropped to the floor time and time again.
Adamek would probably have been KO'd pretty fast by Wlad, because he punches so much harder as his older brother.
If Vitali wobbles Adamek with a jab, can you imagine the damage Wlad's jab would have done?!