It's not that I intentionally speed as much as I just don't like being the victim of speed traps that I have made it my business to know what the best radar detectors are.
For the last 4 years in particular, I've been using various models of K40 radar detectors with the most recent one being a K40 Calibre installed last year. The K40s are special because they are integrated into the car. That is, someone would not know that you had a radar detector. The radar detector itself is installed professionally in the front of the vehicle (under the hood) and a remote receiver informs the driver of any radar threats. Once installed, the read out is part of the dashboard (typically a pair of LEDs).
Also during this time, I've been a daily lurker on many different car websites and the consensus, by far, is that the Valentine V1 is the best radar detector out there. However, the V1 is a traditional radar detector which means it is quite conspicuous there on your windshield. If you're reasonably handy, you can help this situation by hooking it up to a power source in the car, but it's still not nearly as seamless or subtle as a K40.
The price difference between the K40 and the V1 is significant. A fully set up K40 Calibre (with laser defuser) can end up around $2K. The V1 is around $400.
Going head to head
Recently, while driving up north, I got a speeding ticket. The K40 went off but it was with so little notice that it was far far too late (I was the trooper before the K40 went off). So I decided to pick up a V1 and conduct a series of unscientific head to head tests over the past month or so.
So which radar detector is the best? The V1, by far, is superior. It's not even remotely close. The V1 gave off far fewer false positives, seems to be much more intelligent in picking up what matters, was able to detect instant ons that were going on in the distance (The K40 never even went off), and gave far more advance warning.
Eventually, I decided to put them both in the car at the same time. I had read that having two radar detectors in the car at once could cause them to interfere with each other. But at least in this case, there was no problem at all. The two were far enough apart (since the K40 is in the front under the hood) that they got along just fine. It allowed me to really compare the two in performance and like my separate testings showed, the K40 was no where near as effective as the V1.
What I was really amazed at is the lack of false positives the V1 gives when it's in "advanced logic" mode. It really works phenomenally well. The other thing I noticed was how well the V1 handled detecting troopers on the highway who were using instant on to nail targets. The K40 never even picked them up. This evening, while driving up north, the V1 gave me plenty of notice of a state trooper on I75 but the K40 didn't pick it up until after I could see the trooper -- at which point I would have been dead meat if I had been relying on the K40.
So which would I use? The Valentine V1 right? Not necessarily. The V1 is better. No doubt about it. The question really revolves around what is "good enough". For cruising around town, the K40 gives ample notice. And let's face it, for most of us, that's when we get nailed. Going 45 in a 35 or 40 in a 25 is the scenario most people run into and the K40 works very well for that. It doesn't work as well as the V1 but the K40 is completely integrated into the car. I can't do this with a V1. The best I could do with a V1 would be to get a professional to install it up near my visor and put a remote display somewhere which would still be more than I would want on a day to day basis in my car. What's nice about the K40 is that it works fairly well and it's largely invisible.
That said, the K40 is basically worthless for highway driving. I've had my installation checked a couple of times and I am sure part of the weakness of the K40 is how low to the ground it is (since it's installed near the front grill) compared to a traditional radar detector. But I can also tell that it's programming is fairly stupid compared to the V1. So if you do a lot of highway driving, the K40 is pretty useless. So it really boils down to whether you speed a lot when you're on the highway as well as whether the "stealthiness" of the radar detector matters.