Amongst the current choices I do like this one. But without the additional line in the D. It makes it look like an inverted "G" and not an inverted C which is more approiate for Digital "Cash" . I mean the D literally has a DASH in it! If it's gonna be called Dash and you just show the D at some point it's perfect to have a dash in it.
Modified version without the vertical line in the D
To summarize my opinion - The D with the dash in it is Iconic, it defines the brand , the rest just need to be clean and strong letters with no fancy arrows or symbols.
Edit: Just want to mention that if you make the Dash inside the D too short - It looks like an Inverted "E" which is also no good.
Edit #2 - It also makes it look way less speedy and quick! With the long Dash in the D it looks like it's moving fast.