I hear you- I'm sure some manufacturers tried to pass off passive radiators as a fake speaker but they're really not. They're just an alternative to a port. From what I understand every design choice has it's pros and cons and from all the speakers I've ever heard, no speaker is perfect.
I'm not an expert either but from experience I can tell you that a PR can be quite effective if done properly. I have the smaller version of the speaker reviewed below (with half as many 6.5" drivers) and I can tell you that the bass and sub-bass is intense. True sub-bass. Deep, clean and tight. You have to hear these things to appreciate the low end content, it's all there. They will put many dedicated subs to shame.
Here are some quotes from Julian Hirsch (an objectivist deity in some circles) when he measured and reviewed the big version in 1985. Seems like the passive radiator did a good job when paired with 6.5" drivers.
"We have never measured a low-bass distortion level as low as that of the SDA-SRS"
"The Composite frequency response was flat within +/- 4.5dB from 20 to 20,000 Hz, exceptional performance no matter how you look at it."
"Finally, since the IQS analyzer can measure down to lower frequencies than our regular response plotting equipment, we found that the passive radiator response varied a total of only 7db between 12 and 90hz. Polk calls the passive radiator a "sub-bass driver" - with good reason!"
"One of the most serendipitous aspects of living with the Polk SDA-SRS was the rediscovery of low-bass content in many programs. We seldom encounter speakers with response below the audible range. It is quite an experience."
Read the full review here:
https://polksda.com/srsreview.shtml
Now back to separates, integrateds and receivers...