1) Unmend is done because with correct plunge timing, you can travel alongside the Unmend and arrive at the same time, thus getting a free hit. You won't pull aggro off the tank if they are in their tank stance, so I do not hesitate to do this. You are not delaying your first GCD due to Plunge's ridiculously long animation lock.

2) If you are maximizing your DPS, then yes Delirium up time is irrelevant. However, you're never going to be fighting something that doesn't hit you back so thinking this way is fundamentally flawed. Perhaps I am not understanding what you are saying, but I don't see the logic behind delaying the inevitable. On fights like A1S where the first hit is a Royal Fount, this is pretty significant.

3) As with any DoT Salted Earth ticks 0-3s after being cast. It depends on how your timing lines up with the server tick. Putting it down too early could lead to a preemptive pull if you happen to be unlucky with the timing. Better safe than sorry.

4) The 284 mana you get back from using C&S with Blood Weapon is not significant enough to be relevant. If that's your argument, you might as well be using Blood Weapon before Plunge for the same reasons. I use Blood Weapon one GCD later so that I don't clip Salted Earth + C&S.

5) In your rotation, using Dark Passenger after Syphon will result in a wasted Dark Arts and further potency loss when you use Souleater over Delirium.

I gave your opener an honest chance, I did. However I did not pull the same numbers with your opener as I do with mine. In my slaying accessories, I am i190 in all my pieces except my Eso Chest (wish I bought the weapon tbh, but oh well next week) and one i180 slaying ring. If you have similar gear and wish to show me your parse using your rotation while putting out higher damage than me, I will concede my point, but until then the evidence I have gathered myself says otherwise.