What about the possibility that the SD15 Seagate 7200.11 750GB was a mistake? What if HD makers intentionally keep their SATA NCQ algorithm a little crappy, so that people will still buy the SAS/SCSI? Maybe they accidentally had the wrong performance profile in SD15, and 'corrected' it in SD1A. It would make sense that they detune the performance based on what Windows does, but they can't completely screw it up without being obvious in benchmarks or non-compliant. When you use other OSes, or put a smart controller in between, the 'problem' vanishes because you no longer have a Windows access pattern.
This would explain why it seems that some PATA drives performed better than NCQ. Before NCQ, IDE had no way to challenge SCSI's exclusive ability to issue multiple commands. When SATA NCQ appeared, something had to be done to make sure it didn't threaten those profits.
It would explain a lot of these strange outcomes, and why nobody particularly seems to care.
Also, check this list of devices out: Possibly the same problem or related?