Hi:

I would take the SD1 and RUN.....this way no conections between 2 items, the SD1 is one of the best sounding boards still even almost 5 years from it's release, CONS: the screen if you have certain series, you may have it change and that is the END of the problem.

In the Discover board is basically a secuencer w/tone generation and harmonizer, NO styles and you WILL have screen problems, at the store where I work, we have the Discover and also an old VA7,BOTH with the cronic screen problem, it fades after 1-2 hours, also, both are in their second/third screen.....
The Midjay is a little GREAT module.
Hope it helps.