Sarah Kane's work goes over some themes again and again. This "particular iconography", as said in Crave, is a reflex (probably) of her life and influences, literary or otherwise.
But her plays seem to get more personal towards the end, culminating in Psychosis 4.48. Why is that so? In my opinion, her work goes through a process of "undoing". Undoing of the society (Blasted), the family(Phaedra's Love), the couple (Cleansed), the individual (Crave), and finally the undoing of the dicotomy me/you, or maybe of the triad of Victim, Perpetrator and Bystander (Psychosis 4.48).
I am not denying the other huge amout of information and feeling there is in her plays, but I see this line going through all of them, ending in Psychosis 4.48.
By that, I mean she tried to destroy all barriers in Psychosis. Be it character/actor, author/work, stage/audience. There is nothing left, there are just pieces, fragments. This is the process of a psychotic mind, seeing no spaces in the "Other" to infiltrate his self. Perhaps she achieved what Beckett wished to do: "A play with no actors, just the text."
These ideas of mine are still in early stages, though.
And is Hemingway beyond that comparison now, Iain? Why? I don't see the differences between him and Sylvia Plath, for example.