I like the SACD sound and think it is definitely worth it for headphones. No easy way to rip SACDs (check computeraudiophile.com and elsewhere for painful instructions that don't always work) so you would just store a digital copy of the Redbook layer on your computer. The Sony ES reviews certainly seem to make it a viable alternative, but like Dan I doubt you would enjoy the Oppo for this purpose.
Now, having said all that, I still think you want to get a ULN-2 and cut the crap. Get rid of some of those DACses and focus on hi-rez through that route. Way more versatile and offers even higher resolution. Don't play itsy-bitsy-spider with all these DACses for too long because it is just a waste of time and money (let alone sanity . . . glurg, gollum! ).