Yeah, I have no idea how many the squadrons are equipped with now, I remember seeing at least 5 or 6, back in the day.
They were used both as a backup on transits and operationally, "and that's all I have to say about that."
The main problem we had was the brightness of the screen. Some senior NFOs used to get pissed at me when I wouldn't put it in the flight station, saying it was a waste of resources. I responded with "shouldn't the Nav be the one with the backup for his own systems?" There's just nowhere to put it up front, other than the radar cabinet, which is not accessible by the pilots. I would have to twist around about 150 degrees to even catch a glimpse. The screen was bright as hell, and a detriment to night vision. If they ever (hey maybe they have by now) figure out how to patch the display into the tactical screen and integrate the controls into the touchscreen, it would be awesome. Until then, the Nav has plenty of room and he can share it with the TACCO. Me fly plane.