It's worth pointing out that there are a few elements of sound that are used as sound effects in the film but are in fact part of Vagelis's score. These are things like chimes, bells and synth created beeping. Like a lot electronic musicians of his time, Vangelis creates music like a sound designer, he builds layers. Some elements are used, some aren't. An example of this for this collection is 2 different versions of the Main Titles track which I'm releasing.
The so-called "Esper Edition" is actually the worst example in terms of material, construction and a coherent listening experience (which it isn't). It's a kind of fan edit. It uses tracks from already released bootlegs, and combines it with the one disc official release, clips from the film recorded from VHS, and a sound effects track. The sound effects track was recorded for the 1992 "director's cut". It was created for international distributers for language dubbing (it contains all the audio except the dialog track). All these elements are laid on top of each other. But not of it is anything that hasn't been released before.
There's a lot of bootlegs out there with between 1 to 4 disc releases. All have different variations of the other releases, others even have sound effects from the video game included. But almost none of the music is playing on the correct speed and or course none of it is complete.
As well as obviously the new official releases my sources include copies of analog tape. These are great because even although quality has degraded over the years they include a few sound elements that I haven't heard before. It's also simply better for this kind of editing.