The Duo-R and Duo-RX are pretty much identical in terms of functionality and reliability, though you'll pay more for the RX and its included 6-button controller (which most people hate anyway). A SuperGrafx and original CD unit would be quite a bit more expensive and cumbersome, so you'll have to decide if you really want to play those five extra games; another option is a SuperGrafx with a SuperCD add-on, which is a bit more svelte and won't require fiddling with system cards as often, as the 3.0 card is built-in (though you'd still need an Arcade Card for those titles).