Double Right clicking is the obvious counterpart which isn't new at all; the concept of detecting a shift click through the difference of motion in two units (one with a predestined order) and then moving up the queue by canceling the order with the move action- setting it on the path it's supposed to go- is what the concept is about.

And I disagree, double right clicking is far more cumbersome and more clumsy than a single shift click.

Well, you're entitled to your opinion. I see that a Hotkey select (If wraiths are 2) and then a double right click would be far easier for a quick firing of a projectile.'

From 2 - Double Right click
or 2 - Shift - Right click

The left hand slows you down.

Not if you hold it on the keyboard, which many people do for quick group selection anyway.

Or you could combine EUD selection detection of a unit and KEy presse's and detect if a player has unit X selected and key's CTRL + Y pressed.

Seriously? That's like saying that movement in a fps slows your firing rate...

I have however went with a double right click method instead. I personally like the shift-click, but couldn't find an easy way of setting it up for players. I did also notice that while using the shift click method I would hold the key down too often, like when commanding my hero unit to move... ahhh multi-tasking....