Editing of the body or subject line of the e-mail before it leaves while in the Que.
Mail chimp allows editing in the Que and it's one of the few things I liked about them. Anytime my e-mail is about to be sent and it's in the Que and if I have a change to make I simply click on a "Edit" while in the Que and it brings be a few steps back in the process to the place of the text creation and I can edit. Then as I move again forward it remembers when the e-mail is to be sent and you just keep clicking through till the end and it's ready to be sent again. The way 1SC does, it you have to cancel the broadcast, remember to have saved it in a draft.
If not then you have to re-copy and paste it from the Que and begin again. To me the way Chimp does it it's less moves and simpler.