All of RepRapPro's Ormerod kits used Duet electronics, as well as their most recent versions of the Mendel and Huxley. So there are more Cartesian printers than deltas with Duet electronics. I suggest you ask on the Ormerod forum if you want to know more on this subject. There is also a recent post in the Prusa section of this forum from someone who built a Prusa with a Kraken head, controlled by a Duet+DueX4.
Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod
Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].