Thanks for taking a close look at that PSu! I've been using the 12V 300W version (which is fanless) of a similar power supply to power my printer for the last 6 months, with no apparent problems.
Was the ripple really as much as 1Vpp? It looks a lot less on the scope trace in your blog entry.
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].