I've had the DAC for 2 weeks now. Far better than my Apollo. Some say it's better than the Saturn, some say it's a bit different but equally good. I haven't lived with a Saturn, so no opinion from me.
If you like Rega, particularly their sources, you should make it a point to hear it before deciding on a Saturn or Apollo.
As a heads up, I've read that Rega is planning on revamping a bit. The Apollo and Brio's replacement will be in a half width chassis that's shared with the DAC. The Mira and Saturn will get a facelift, but remain full width. No word if it's purely cosmetic or internal too.
This came from a Rega rep on Pink Fish Media. They're supposedly due out sometime this year. I'd guess later than sooner.