Recording engineers tell it like it is

[BTTF]

I am going to switch gear more towards audio on CDs though still related to movies..

I have always been curious- As more and more classic albums get 5.1 surround mixes (a GREAT example is Queen's "A Night at The Opera"), many are being released as DVDs in 5.1 (like my example- videos for every song, commentary, etc.), as well as having a new 2.0 stereo mix for the CDs.

My question is- when one approaches this, pound for pound in an A-B comparison, which 2.0 would sound better?

1. A song that was mixed for 5.1 and then downsampled/converted to 2.0?
2. Re-mixing specifically for 2.0.