Yes, I plan to try out one of my IR boards on the Mini Kossel. If I can get it working at least as well as the mechanical probe, then I may develop a new PCB that is more suited to mounting on the effector plate.
Another Z probe solution I considered for the Ormerod was a solenoid activated probe. There wasn't really space for it on the Ormerod, but there would be on the MK. I'll need to check the weight of the solenoid I have in mind, but I think it is much lighter than the hot end.
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].