My personal opinion is that sometimes a Frequency Shift feature can be helpful, but it is not the main method I use to calm a noisy detector. Yes, it can help, but I also have used makes and models with a frequency shift that showed a little bit of degradement in performance. Maybe things are a bit different with these newer all digital detectors, but I had a discussion with an engineer, from another company, who detects a lot himself and used the same model I was using and we got to the benefits of a Frequency Shift.
His comment was that if it was important to use in order to reduce interference, do so cautiously. If you are detecting near another person who has a detector that is causing the problem, the first step would be to move away. Next, let the other guy shift his detector's frequency, if it has that feature, and third, use the frequency shift as needed.
Note that I seldom have noisy operation of I 'get-out-of-town' and away from EMI issues, and even in town I don't always have a problem, often running with the Sensitivity between 95 and 99 without a lot of chatter. At times, however, it is difficult using some detectors with an increased Sensitivity setting because they get a little chattery. Some models have a factory preset marker that is below maximum and at a point that is usually comfortable to search at. One example would be the White's MXT and M6. In many sites I can increase the Sensitivity/Gain to maximum and it might be a bit 'on the edge' but not too noisy, and then there are times I need to use the factory preset setting, or even reduce the Sensitivity/Gain to about mid-range.
The Gamma turns on at a Sensitivity level of '80' and the T2 turned on with all three functions set at '60.' Usually, if you increase either of these models to maximum Sensitivity, in an urban environment, especially, they will be noisy. The G2 and Omega, however, both feature a variable control that is the On/Of knob and Sensitivity level, and neither has a factory preset Sensitivity setting or suggested preset. Therefore, we, the operators, just need to increase the Sensitivity level to a point where the detector is as high as tolerable and just below being too chattery and unstable.
The T2 has 7 Frequency Shift settings, with '4' being the turn-on default frequency, and you can shift off the base frequency up or down three settings. It is useful, at times, but I still seldom use it. Instead, other than relocate to a quieter environment, I just reduce the Sensitivity level to stabilize the detector. I do the same thing with the Omega.
With the Omega, which has this feature, and the Gamma, which works similarly but doesn't have a Frequency Shift, I intentionally worked a few sites to see if there was any real improvement in performance. I ran the Gamma right at the point of instability and then the Omega, but used the Frequency Shift settings. Usually there was a different audio response or 'pulsing' sort of noise, and it sometimes got it a little quieter, but I then had to reduce the Sensitivity a little to match the Gamma at a similar audio (almost smooth) and the performance was very similar. I then used the Omega without changing the Frequency, leaving it at the default f1 and only reducing the Sensitivity level. When the two detectors matched in stability, it was very difficult to tell much difference in overall performance.
Here is a cut-and-paste of the Omega's Owner's Manual regarding the Frequency Shift function:
[size=large]FREQ: Frequency Selection[/size]
Use this control if detector behaves erratically and you suspect electromagnetic
interference from some other electronic device. This control will change the
detector
