With the FieldFox line of products gaining better and better VNA performance(Just saw the new B models) have you considered adding the more advanced ECAL options to the firmware?
A very useful feature appears to be missing - end user characterizations. It would also be nice to support the ECAL confidence checks.
I have an N9918A and an N4691B. As my N4691B has two female connectors the end user characterization would be very useful.