You make some good points, however I think it's much harder to compare these to a simple Hikvision OEM camera.
For starters, metal detectors don't have much value if nobody is there to man the unit. If the unit goes off, somebody has to stop the person, instruct them to try again, or ultimately scan them with a wand (and then also react accordingly if it is a legitimate threat).
It would seem that someone who determines they *need* a metal detector, would also have the cost of 1 or more guards. Is it really worth it to save a few thousand dollars with a cheap unit like this in the grand scheme of things?
Also, as I touched on in the article, metal detectors require some initial setup/calibration, and ongoing checkups to ensure reliable operation. If someone is looking for the cheapest option, it would seem that the odds they neglect to perform (or hire out) the proper ongoing maintenance are high. Then if the unit fails to detect something, will they try to come after you the integrator, ADI/W-Box, all of the above?
Yes, I'm sure you could have a contract that limits your liability, but we all know that "limited liability" doesn't mean "free of hassle and frivolous lawsuits" all the time.
You also make two statements that highlight part of the problem (IMO):
Like anything else, a careful examination of a product before installation is necessary.
As I mentioned, I do not know much about these detectors.
Are you, and other similar integrators, in a strong enough position to recommend and install a walk-through metal detector for clients that have a need for one?
Do you/would you trust that ADI has found the most fool-proof and low-cost unit that removes some of the need for you to do your own evaluation, or do you think that they've mostly just concentrated on the "low cost" aspect?
If you run into problems, which tech support line will you be able to call? Will the ADI folks be able to efficiently help you troubleshoot this?