Visual?
Did you tell the"traffic" that separation was being eroded? Did you tell "traffic" that TCAS would no longer be functional against non-transponder? In the UK we are prohibited from using visual separations of the type you suggest if Radar is available....and even with a visual confirmation of an opposite direction pass by both pilots we still have to wait for 5 miles at London ACC/Swanwick.....it helps with wake vortex spacing, but more by default than design. Don't know if your kit is similar but if I am running two on parallel headings I may put on a Range and Bearing hooked on to the pair to monitor the distance......it only reads in whole miles.....whereas the snitch on the supervisor's desk reads to a tenth.....wrong priority springs to mind!!!!!!