Lots of talk about remasters and compression and EQ and all that around here lately, but what it all comes down to is that sound quality issues are highly subjective and if it sounds good to you, that's all that matters. But if you want to go further ...
The 1999 David Bowie remasters have more compression than the originals, which is easy to check with many wave file analysis programs, and I have. In the range of 20% more, which isn't that big a deal. For instance, just a quick comparison between the song "Black Country Rock" using the Advanced Normalize/Compression function in Audiograbber shows the Rykodisc version with an average level of 64% and the Virgin at 81%, both normalized to a max of 100%. The Rykos don't seem to be much different than the originals in compression, but I didn't have any of the albums in all three CD versions at the time I made the comparison. Many remasters are compressed much more though, especially if the originals had a lot of dynamics, which the Bowie albums didn't, for the most part. Most people seem to like the sound of more compression because it does tend to bring out some of the sounds that you might not normally notice as much, and gives them more apparent punch. But I find the 1999 Bowie remasters to sound a little congested, and bloated in the bass, and the cymbals sound kind of like splashes of white noise instead of shimmering metal, especially if compared to the not so great Rykodisc versions from about 10 years earlier, which on my system have quite a bit more airiness and frequency extension. But on their own they don't sound bad, and I know many people find the Rykos to be too bright and lacking in bass, and the original RCA releases, while prized because of the flat nature of the transfer, are generally believed to not be taken from the masters.
And Ziggy was further messed with a couple years ago with a new remixed 2-CD issue, and also the SACD. I think it was done by Peter Mew. I know that markl has said that he likes that one a lot.
Be fun if you could find a fellow Bowie fan and exchange a couple songs from the different versions and do your own comparison. I have the whole set of 70s albums on pretty nice sounding RCA International vinyl done in 1980 by Bilbo at Tape One mastering in the UK so don't care that much what happens to his catalog as he tries to keep it "modern sounding", but it would be nice if at some point an attempt was made to do a true audiophile transfer to digital with none of the EQ or noise reduction or compression or other processing steps, just for those of us who still like the "old sounding" originals