I just picked up a V1.7 (2.690) with a concealed display for a little over $70. I tested it out on 2 known K band falses today. It outdoes my V1.8 and my other V1.7. It is astonishing how sensitive it is on K band.
One thing I failed to notice on my other V1.7, and I'll have to check. There is a dot to the bottom right of the bogey counter, very small. It was on when the alerts were on. I checked the manual and it says if the little dot is not on during an alert it's X band, if it's on during an alert it's K band, and if it blinks during an alert it's Ka band. To be honest, at night that is a better system for band id than the single leds that you have to discern which one.