I don't understand all the things you said:
"I really do not think Fab can compress Bluray at all."
But Dvdfab can compress a blu ray to BD50, BD25 1080p, BD9 1080p, BD9 720p or BD5 720p.
And it works very well.
I've a PS3 system and DVDfab is pretty good to compress Bluray and to copy on the pS3 HDD.
I prefer BD9 or BD5 because it takes few GB (4.5 to 8 GB) on the HDD and these a good quality (better than a regular dvd).
I tried with another blu ray (wolverine) to be sure (It could be a problem with the new 6220 beta) and do not have any problem as cold prey 2.
So I don't understand why dvdfab can't compress this movie.
If someone can help...