These are very interesting findings. Logic would dictate that the original/native, industry standard format for 3D would represent the best possible format - in this case, 3D Blu-ray (frame-packing). The creators of the format have chosen this method of displaying the films, and the encoding from source has been optimised for this output.
However, what the professionals who author blu-ray movies may not have considered is playback on a dual-screen device, as opposed to the more traditional Active/Passive 3D TV/Projector methods.
In these special circumstances, Full Side-by-Side 3D video seems to actually represent an equal or better alternative to the original frame-packed, sequential method.