They'll move hides anyways, light or heavy. The only concerns I can think of with really light hides is that a lot of snakes like to laze about or use the "roof" of the hide to hunt from. Lighter hides might collapse or tip over which isn't a nice experience for your snake. The hides you are using are light in color. Hides are better contructed of dark material to keep as much light as possible from filtering in to your snake while it's inside (makes the snake feel more secure...secure snakes are happy snakes...happy snakes eat better). Tall hides leave a lot of useless head space the snake neither needs nor wants. They also allow heat to rise in the hide above where the snake can effectively use it. They also are more likely to tip over being both light and tall in construction.