I had a problem with Frame strata too on my layout, but that was because when creating Backdrops I was giving them Frame strata Low. Then some other elements of the frame were giving higher Frame Strata, dunno how because before they didn't behave like that. I removed the Frame Strata (Low) from the Backdrop and everything spawn "normally" again. Don't know if that is your case tho.

Has something changed regarding frame scaling? Prior to 4.0 my frames would scale accordingly with the .scale property but now it just ignores it.

I had to change that on my layout as well.

Use this instead:

:SetScale()

The eclipsebar seems to force visibility (on form changes etc), meaning I can't control its visibility once its spawned.

Edit: Nevermind, this seems to be the case with more things (castbars etc.)

The eclipsebar element uses the same visibility settings as the default blizzard element. The element will be shown if you are in balance spec and in caster or chicken forms, any other combination of form/spec will hide the element.

If you want different behaviour then add your own PostUpdateVisibility function:

Oh, I didn't know that was possible. Thanks, and appologies for my noobishness. :)