You will most likely need to change out the base chip and the game chips...I was thinking just the base chip initially, but then seen a 4.0 set that had game chips for SD and a set for MD.
But the good news is, that is a relatively common set, so it should t be a big deal to find them. I may have them, as I am wading through some GK software right now. Otherwise, Ken @ Ohio can probably help you as well. I believe it was Ken that posted a spreadsheet of GK sets not too long ago, and that was one he had listed.
And yah, with MD, you get a wider game selection, as you can have different games at different denoms.