sound sacd discs like dsd Cds?

I was wondering how a DSD recorded rebook cd sounds compared to a sacd played on a sacd player.
Listening to that particular SACD on my SACD player (a modified Sony SCD 777ES, with an Audio Logic output stage), on both the redbook CD and SACD layers, the redbook is pretty close, but falls a little short in terms of decay of instruments and smoothness of voices. A little more etched. Same result, though even less pronounced, when the redbook layer is played back through my Forsell/Audio Logic combination. And keep in mind that the Audio Logic converts pcm to DSD internally, too.
The maximum signal level recorded on a SACD or a DVDA will be the same as the maximum on a CD. In other words, bit 24 of a DVDA represents the same player output voltage as bit 16 on a CD. So what you gain with "high res" is less quantization error for the quiet passages, where only the less significant bits are being used. So if you have music that is mostly loud, probably compressed, the 16 bit CD and the 24 bit DVDA will sound pretty much the same, neglecting improved high frequency response due to 96 KHz sampling. (I use the PCM encoded DVDA as my example because the comparison to PCM encoded CD is straightforward).
Although I didn't do the explicit comparison I would guess that the mastering on the CD layer of the SACD is exactly the same as the mastering on the RBCDs.