I think the empty spot on ball stopper is a great opportunity for mods. Not worried about it. Same goes for the space where Krang is.
I found the Van lock on the Premium to be underwhelming. If it was more interactive like Groot, and accepted balls for lock as well as released them, then that makes a difference. As it stands, it just holds the balls and the door opens and gravity to pull them out.
That, given with the fact that the pizza works almost exactly the same, and the excellent light show is the same, the Pro is where I choose to go this time.