The varied shapes definitely make it more fun add more of an interest in adding it to the puzzle so I agree with you there! I think having them come up rarely is fine and its like a really nice piece for big points kind of deal. The piece stacking is kind of unique to the game and has added interest to me, and makes it so its easier to balance particularly in the early game where not having enough land would become a very large problem if they cant stack. So visiting that would probably take a lot of rebalancing. Not sure though! I don't think cutting out the overlap would add too much and it doesnt take away from the gameplay. Currently it just is a sacrifice of points for space, and I think thats a fair tradeoff