Possibly. The other issue is stereoscopy which I am also considering. In that case (barring post-process stereoscopy which I do not like), using render textures and scene quads is my only option if I want to control depth (I've shipped stereoscopic games in the past, neutral depth UI on far-focused scenery is *horrible*). This would only be an option, and I'd want to be able to fallback on the default method for performance reasons (especially on mobile where stereoscopy is not a possibility)

The matrices of noesisGUI elements are full 4x4 matrices. You can apply perspective and z layering. I think that you could achieve what you want without using render to texture. The unique limitation is that we ignore the zbuffer.

This might work, true, though it's also a question of whether I can do it within the confines of Unity where all stereoscopy support is 3rd party. Still in the exploratory phase, so it's all worth experimenting with.

Though, you say it's ignoring the Z-buffer; that might actually force me to use render textures anyway for the status boxes as they would need to be obscured by scenery (not an issue for the rest of the UI though).

Yes, if you need panels hidden by 3d scene objects you have to use quads for now. Although this is something that could be improved in the future, we didn't find time to investigate it yet.