The UltraChrome - Eboni-6 incompatibility was a specific problem I was warning against. Note that Eboni MK and the generic base are compatible with UC inks, but not the base MIS uses (or originally used) in Eb6. The 1400 OEM Claria is not a problem with Eb6.
That said, Jimbo is correct that it's probably always best to flush. If you have some of the generic base, that works.
I find it takes 2 cleaning cycles when I switch from color to B&W in my 1400. (I generally don't flush.)
Paul