The blu ray discs use either MPEG-2, H.264/AVC, or SMPTE VC-1 as codecs.

I'm not an expert but I think that if you film with with film, convert into digital to do special effects and post production, and then convert back to film for the cimema, you are going to loose some quality as digital data can't replicate something that isn't digital exactly. If you filmed in digital and converted into film, then you loose quality too, as you can not make an accurate reproduction of something that is digital by using a medium that is not.

I don't think you are going to get a conclusive answer. Its like CDs vs. records vs. tape. Some people will always think one format is better.