Correction to what I said - scenes saved in 7 will probably work fine, as there have been no major changes in the 7 dailies yet (mostly it was stuff that was then ported to the 6 Hotfix 1). I initially saw this as being version 6 scenes loaded into 5, where there could well be problems :)
Still no guarantee that anything using 7 will work, but right now it's probably fine.