I always have standbyscreen enabled, in combination with Billboard. Really outstanding feature on N9. don't know how much battery it uses, have no problem. But would like to have it integrated in powersave mode PSM on = stanbyscreen off, like it's on N8 for example. Maybe they didn't implement it in PSM cause battery usage is really low, so no need for that? But a way to quick switch on/off would be great.