With that being said, does anyone know anything about the quality of the new American Blu Ray?

I have it. The PQ is better than the Italian one; however, the audio is still the (rather horrible) 5.1 upmix, which suffers from the following issues:

Dialog censorship (it seems to be based on the censored audio track - the Italian is uncensored).
(Reportedly) wrong music cues used for the final flashback scene (again, the Italian disc is correct here).

So a project to sync your English mono track to the MGM BD would be probably a good idea, given that the MGM has a better PQ.