The old click macros were good, because they were highly configurable.

If we go the route of two castsequences, and alternate between them.
We could as easily alternate between several castsequences.
And have our mapped key (or just manually use the keyboard) sends 1-2-3-4 (four step, for example).

If nothing is on a key, it cannot fire.
If you want the Backstab in the rotation, drag it in... etc.

Not sure exactly how to get everything to work, but I really liked how we could change the order (priority) or pieces (Call of the Elements, for example) of our spam by dragging something into a slot or moving it out.