When I started downsizing my Genesis collection, the first thing I did is get rid of all my loose Genesis carts. But I took a small handful of "top-tier" titles and kept them aside, meaning to hang on to them until I managed to replace them with CIB copies.
Tiny Toon Adventures: Buster Busts Loose
Streets of Rage 2
Double Dragon 3: The Arcade Game
The Revenge of Shinobi