Yes, stickerless cubes should be allowed in competition
No, they should not
Could somebody with a stickerless cube try inserting a small piece of black paper between the edge of each piece? Just enough to cover the furthermost edge... Edges would be fine for providing an example of showing whether my idea works or not.
If my idea works it should provide a method of using stickerless cubes without 'additional info'.
The problem with this approach is that each stickerless cube used would have to be verified by a delegate, or perhaps just the scramblers/judges.