I have been cruising around Northern CA for over a month with an RX65 and thought it would be helpful to some readers to share experiences and impressions.
My main reference point is an Escort from about 1990 or so. It is the unit that had Cincinnati Microwave's (prior to name change) first DSP chip. Compared to that unit, which only detected X and K, the RX65 is much quiter, probably a combination of lower sensitivity (that Escort was extremely sensitive) and higher selectivity.
The main learning has been that CHP uses exclusively Ka around here. I am currently running with X, K, Pop, and Ku disabled. When the detector goes off, it *is* a CHP and I know I need to respond to the alert ASAP. I have had zero falses on Ka thus far. Inexplicably, the detector goes off infrequently on K band even though I have it disabled. It is rare, but I've seen that happen perhaps 5 times. (No X alerts with it disabled.)
I find that threat mode is the best. When trying to detect all bands it shows you the three bands separately with a nice 1-9 scale. When trying to detect only Ka I still like it because it shows the more precise 1-9 scale rather than the standard mode which has fewer bars. If there is a use for TEC mode, which shows the exact frequencies, I have not found it yet. Any Ka alert is a real threat, and the frequency does not matter.
With POP detection enabled, I have averaged about 3 falses per week. This was not as bad as I had anticipated based on others' comments. I think only once was I speeding and vulnerable enough that a POP false scared the pants off; usually it happens when you are just sitting in a pack of cars or crusing at low speed on a side street.
I have had only one laser alert that I thought might be real. It was a false, no threat in sight. Driving around 237, Great America Parkway, and the San Mateo bridge brought a nearly continuous series of laser falses. I don't know what the source of these falses was, but this is a very dense metropolitan area, so it could have been a number of things.
Usability has been great. It is loud (I measured about 86-88 dB in my car), and I find the alerts clear, penetrating all but the loudest music. It does not audibly distinguish mild threat from extreme threat as clearly as my Escort did, but frankly any Ka threat is SERIOUS... get the speed down immediately. Visually it is easy to read, and I like the levels of brightness abailable.
Encounters with CHP (up to about a dozen now) have demonstrated capability to detect instant on bouncing off of other cars a good half mile down the road. Constant on signals are easy to detect, but you need to beware instant on shot from behind on on-ramps. You may or may not get lucky depending on the timing and position of the cop, the target, and yourself. So far so good... I have not been instant-on clocked without warning. I believe it has saved me two tickets, one from instant on, one from constant on (cop was well hidden). The alert may never exceed 3 out of 9 if the cop is running low power from behind, but I have seen 8 or 9 when getting hit full power from the front. By the way, I have not encountered laser yet, as it is used only sparingly around here.
Bottom line - if you know that X, K, and POP are not threats, the detector literally becomes a 95+% accurate indicator of threats - only an occasional laser false and the rare K band alert (though disabled) keeps it below 100%.
I highly recommend the RX65 based on my experiences. I've tried all modes (highway/city/auto) and all displays, and I've enabled and disabled all bands except Ka (always enabled). It works brilliantly.