I think susanoo arrow is faster because kakashi(one of the fastest ninja in the world) wasn't fast enough to dodge it but hebi sasuke was able to outrun amaterasu for a period of time
Do you agree=D?
Yes, I agree.
Itachi didn't have the intent to kill so of course he didn't spawn it on him...
I love it when people make up their own mechanics for MS abilities. /sarcasm
No it isn't.
If it were instant, then Sasuke and Ei wouldn't had been able to dodge it, and Bee wouldn't had been able to stop it from igniting his head.
It's a fireball. It was a fireball against Sasuke, it was a fireball against Ei, and we had a zooming effect on Bee as if something was coming towards him right before he blocked it.
If it were instant, then Sasuke would had been trying to jump out of the way of his burning shirt. That isn't what happened.
Also, logically it couldn't be instant or else it would literally be an instant win against most characters, which would mean Sasuke was and still is more powerful than Naruto as soon as he got MS. But no, we're told that MS Sasuke = SM Naruto, and even now they are still rivals. And Naruto's the star, so there's no way Sasuke's going to be more powerful than him.
Itachi hit Sasuke on his back simply because he knew that Sasuke could do the rebirth thing that Orochimaro does...
Remeber they were comrades for sometime...
So Itachi did intend to hit Sasuke with it, and Sasuke dodged it.
Also, Sasuke may had wanted it to ultimately hit him since it and oral rebirth were part of his plan to set up Kirin.