Ickathu
Veteran
I think for BLD, transparent and pillowed cubes should not be allowed. With a pillowed cube, you can (theoretically) see an entire layer at once/4 sides. This allows memo to be faster since the cube is rotated less. Transparent cubes allow you to see all other sides, and if the cube is transparent enough, this could lead to a no rotation memo. Stickerless cubes do not make anything else visible for BLD purposes.
For 7x7, I agree that pillowed is fine, for the reason that Bob said.
For 7x7, I agree that pillowed is fine, for the reason that Bob said.