I don't think that you can necessarily shout bias with the results of this test.
First of all, remember that Lidatek persuaded many (if not most) people in the latest group buy that a single transponder should be sufficient.
This is an excerpt from a post by atomic80 during the last group buy describing his conclusion after talking with the Lidatek people while they were installing the LE30 in his car:
---
While Kit went to work on installing the LE-30 in my M5, me and Andy had a lengthly conversation about it's operation.
An issue that I came up with was whether or not to go with one or two transponders, vertical or not. I decided that one horizontal transponder would be more than enough to suit my needs. I came to this conclusion based on the fact that most police officers will find it nearly impossible to accurately aim at your car especially from 200+ feet away. I tried doing it myself and believe me when I say that it's HARD aiming that tiny red dot at the car from 200+ feet away! The LE-30 transponder does an excellent job of providing plenty of coverage. What it does is fire off a "cone" laser pulse which will do it's job. It also has a "cone" scanning field too. The difference between the LE-30 and the LE-20 is not only the depth of the transponder unit itself but also the sensivity factor too. It's much harder for the transponder to detect lidar pulses on the edges but the LE-30 does a better job of that. Also, I wanted it to be as stealthy as possible and having just one transponder under the front bumper in the grille around is perfect. Having two vertical transponders or even one will do the trick but will be a bit more obvious. So, either way will work depending on your own preferences.
---
Whether a system uses one or two transponders (or 4 for that matter) is a matter of system design. I think I would liken it to manufacturers choosing different engine technologies to achieve the same goals (i.e. high power, high reliability, more sales) -- some choose a normally aspirated V8, some choose to put on a supercharger, some choose to put on a turbocharger, some choose to put on two turbochargers, some choose to put more cylinders in and go to a V10 or V12. These are design considerations that are made by the manufacturer. You can't discredit a 1/4 mile time test solely on the fact that one manufacturer chose to put two turbochargers on their intake while your car's manufacturer chose to go normally aspirated. In the end, when you go to test the two cars, the cars are what the cars are.... Of course there are tons of other (some subtle and some blatant) ways to bias tests, but just because Lidatek chooses (for whatever reason) to promote its unit as being effective with a single transponder and Blinder chooses to use a two transponder system as its most basic configuration shouldn't be a reason to discount the results of a test out of hand.
The other comment I wanted to make is that while radarbusters.com clearly has a sales agenda, I think that the company that actually does the testing is Speed Measurement Labs. I don't think they sell anything at all. I'm pretty sure they make their money by consulting (to both the detector companies and law enforcement agencies simultaneous, interestingly enough) and training. I remember meeting the principal of SML at an NSX event back in 1998, I think. He was very knowledgeable and did not appear to be biased towards any particular brand of product. But I remember him stating, even at that early juncture, that laser detectors would be useless against the laser guns and that you would need an active jammer in order to get any sort of protection from these measurement techniques.
I will have to say that I have used the Lidatek LE30 product for about a year now on two cars and it has saved me twice. I have no doubt that it is effective. But I did use two front transponders and, as mentioned above, with this configuration the cost is significantly higher than the Blinder product. Looking at the results of the above mentioned test makes me fairly confident that the Blinder product should be at least as effective as the dual transponder LE30 product (and more effective than a single transponder LE30 product) at a better price.
The engineering compromise that Blinder appears to have made is that their transponders are noticabily larger than the LE30 transponders. I have just received a Blinder X-Treme M20 today and will photograph the physical unit differences soon.
David