At least on my Sony Xdr-S3, there was no stereo during the KXA tests, despite the promo about how there would be. That could be a drawback of the Sony, but I assumed that the source material was all mono. Incidentally, I know the test was heard in Seaside, Oregon near sunset.
I was really a fan of AM stereo, especially the Kahn system. I lived in Bakersfield in 1983 and won a Sony portable from KHJ. Great nighttime stereo reception from KNBR, KBOI, WLS and others. And yes, Andy, much better than HD and compatible with all radios.