I have a feeling adding an alternate split screen version might push the size up too far, as it would necessitate more than one version of the film on the disk (whether it's a small 'picture within picture' version, or a full split screen version). I suppose one thing Ady could potentially utilise if Blu-Ray authoring allows it is an 'interactive mode', where in key scenes that have had the most changes it would tell you to press a button on your remote to see a VFX breakdown. That'd be cool.