So, I ran into the "freezes at 50%" problem with a LiteOn IHOS104-06 (just a couple of months old, and generally well-reviewed on NewEgg). I rely on AnyDVD to remove HDCP so PowerDVD will actually play back my disks, but from what I can tell, this makes no difference at all.
I ran ImgBurn on our NetFlix copy of Avatar with "Ignore Read Errors" enabled and AnyDVD disabled... and it worked. Mostly. It took 115 total retries, with one sector that it gave up on after 20. All of these errors occurred in the first chapter (or thereabouts) of the second layer, with the drive reading at speeds as low as 32 KB/sec (and stopping altogether when it errored). It was only this one small area that had problems, after which the read speeds came back up to normal and the copy completed. I've posted the complete log from ImgBurn in case anyone is interested.
So for those of you having this problem, I highly recommend giving ImgBurn a try. It will take a lot of patience, but you should end up with a largely playable (or ripable) image.
But in closing, I'm still dying to know: WTF is up with this batch of disks? What makes a PS3 so special that it can play them just fine, while a multitude of different PC drives crap themselves?