Accuracy of Replays


Maybe someone can help me clear up things. I´m having a discussion with a guildmate, for the second time now, over who of the both of us was faster/infront of the other on playing mechanics.
First incident was on Mistress with Hydrashot and the second on Avatar with the Blades.

We weren´t sure who of us was in front of the other and didnt stand still while beeing targeted by Hydrashot. Im saying i was, he was saying he was. Second time now on Avatar and the Blades. Im saying he ran into me and vice versa.
To sort this discusion he used the replayfunction of his logs.

So here my question: Are his logs created by his combatlog? So is there a delay of my action in his Log? The same way im infront of him on my screen, and he is in front of me on his screen. Or is the replay neutral?

Hope you can help me.

Any help possible?

The replay positions come from the server and not the client, so they should be accurate at the time damage is taken.