SD4 Dual Extruder Mod?

Ive been checking out the boards on this website http://www.smw3d.com/3d-printing-control/ (Which is the same guy on ebay that sells the E3D V6 for 79.99 and hes really cool) and Ive been thinking about converting to a Ramps board since he has the 1.4 for $42 but then I saw this new Rambo board. He also has the power supplys for very cheap and it got me thinking.

I was just going to buy the DaVinci 2.0 or the workbench from solidoodle. I enough for the Davinci now, but what if I just threw all of that into my SD4? Changing the Motherboard seems almost trivial.....The hardest part would be mounting it in a new location for me. (which isnt much of a problem with a 3D printer at your disposal) But are there any Dual carriage mounts out there for the SD4? Could you buy a workbench carriage?

If anyone has any thoughts please let me know.