I think it depends on your perspective.
My view is either Ka or X. Why would I say X-band? Because nearly everyone mutes out X on their RD. So, if you do encounter Officer Rumplestiltskin who just woke up after 20 years in the 7-11 parking lot, you're screwed.
Other than that, I think Ka is tough because it doesn't travel as far as K or X, so you're not going to get as much warning.
Now then again (sorry, I know I am rambling here... not enough caffeine yet)... I have encountered some nasty K band Genius units that seem to have a really narrow beam width. At least my V1 had a hard time with them when Occifer Fythe's patrol car was not coming at me head-on. That really scared the crud out of me, because it was K-band. I did get some rear V1 warnings from scatter awhile after he passed me, but not much.
Note the area I was driving in was very flat, so no issues with terrain.
Not sure if I should be scared of that K-band or of my V1.
Anyone else run into this problem?
Is this just real low power K? Anyone used/tested it. Genius 2 units. I may have to get one to try it out. I had written off K-band with a yawn until I ran into this scenario. I would like to know what the range is on those things (from the operator's perspective).