I like owning all the official carts and a multi-cart for the rest unless there's something super awesome to me which..dammit, e5frog's stuff is so nice i do buy the separate carts too..lol. but truth be told, the multi-cart is what i use the most for the Fairchild and my verctrex.
to each his own, nothing wrong with any way you wanna play or collect. i dont think im getting the plus of a 3d printed backbit is it cheaper to update with a new board versus buying a whole new multi-cart or that is can hold multiple multi-cart boards depending on what you wanna play thats the bonus?