From a toolkit perspective, I see Cheatin' punishment come in three general types: Hard, Soft, and Mixed.
Hard punishment is for winning the shootout now, useful especially for repelling an aggressive deck using spot removal against you, or attacking a deck now that needs time to set up it's pieces before they fall into place.
Soft punishment is for exploiting an opponent's tight structure (or bad luck on draws) to gain some board advantage, but doesn't alter the outcome of a shootout it is played in. Generally a card you expect to play to give yourself an edge over the long game.
Mixed punishment lies between these two, now acting as both hard and soft, now acting as either hard or soft depending on the context it is played in.
I think it's also worth noting that I don't think many CRs fit neatly into one category without considering the deck they are situated in, the match-up they are set before, and the pilot's pre-conceived or developing game plan. For example, as Will mentioned above, Bottom Dealin' has it's luck factor reduced the looser the deck it hails from, and similarly This'll Hurt in the Morning loses it's punch the tighter the deck it is played against, and many CRs can be one or the other depending on how exactly you use them (do you boot their shooter in lowball with Coachwhip!, or do you wait for them to come fight you in hopes that they cheat!?)
Anyhow, my opinion is that the game is ready for another of the former on a different value than 2, 4, 8, J, Q. I'm not sure what I would want it to do exactly, except as loosely defined as "hard" to render other values as for meeting this deck-construction benchmark.
In deck-building with my playgroup, there have been several instances where we have worked out a new deck almost all the way through, then proceed to situate the deck with CRs only to find that all the "hard" ones are already dispersed across different decks!
A new idea: Reprint a tried-and-true "hard" CR (such as Coachwhip!) under a different value?