I already tried that, but he's so far out on the edge that the soldiers from the alley entrance will have immediate line of sight to him.
The soldiers on the opposite side of the alley will eventually have run around Surkov and gunned him down from behind.
Also if I would place myself on that side, I wouldn't be able to fire at the soldier on top of the roof infront of him to the left.
With the talents I have chosen I can't take down the guards in such a fast pace before he dies.
Had the same trouble on my first playthrough. As soon as you come out the door and all the guys line up chain shot, the focus on all the guys on the left, assault rifle and grenades work wonders. Then it just becomes a game of killing as many as you can, once you meet the check the conversation will start, so focus on the weakest ones. BTW, this should be on the spoiler section.