As Apple is currently modifying the support for Quicktime VR under QT5, that question can't really be answered. Personally, I do prefer Apple's own QTVR Authoring Studio against VRWorx which is far more buggy and unstable. QTVRAS doesn't currently support cubic VR's but I would expect a new version of it pretty much to coincide with QT5. The current QT5 Beta expires on the 14th of April so something is pretty imminent!!
Yippee!!