Think I agree; the z-channel checkbox was probably put in to fill an otherwise empty space. When I render as softimage (pic) I get the separate z-depth files (though in a different folder) but even when I move them to the same folder as the image files Adobe after-effects doesn't display a z-channel (it's supposed to automatically import the depth files with the images as long as they are in the same folder)
I think my lack of knowledge of After-effects is to blame here.

Spamming my thread? I have no idea what that means, but it doesn't sound very hygienic. LOL

Any help here will be appreciated.