Quoted from Jam_Burglar:
I felt like the color DMD added a lot of value in that it's easier to digest the information (for me) when it's in color.
One of my favorite mods is the Bigfoot Spotlight mod. It integrates perfectly, interacts with play, and lights up that area when Bigfoot is doing his thing. If you're going to put LEDs in the machine you really need the OCD boards Herg makes. White Water has a lot of fading and scrolling effects with the lighting and you need those OCD boards to preserve that.
I would add the missing mountain mod to this list.
If you do LEDs, consider Pinball Bulb's GI upgrade kit to light up the middle of the playfield.