I was thinking of upgrading my Ryko discs with the Virgin ones for MWSTW,Hunky Dory,Heroes,Lodger & Scary Monsters. I wanted to know if the sound is better on the Virgin discs over the Ryko ones.

IMO Ryko > Virgin would be downgrading. to upgrade go back to the original RCA CDs.
for TMWSTW and Scary Monsters either the US or Germany discs are fine.
for the others, Germany all the way (the US have problems).
expensive but worth it. however, deluxe editions of all the albums would appear to be in the works, so it depends if you want to wait (could be years of course).

Thanks for the info. I'm going to seek those out.