I've had these for a couple weeks now, and have only got several dozen hours in so far, but I really like these MDR-Z7's. Without saying which is better, I'd say it's tonally closer to the R10 than the CD3000. I've been using them exclusively out of the NuForce, and I don't hear the bass bloat that purk talks about (it's not prominent, anyway -- it is slightly more bloated than the R10s [from memory], but certainly not PS1/Leatherhead/DT770 territory). They're fairly straightforward, and epitomize the boring sound that I appreciate so much ("if they sound boring to you, listen to more interesting music"). I certainly like them (from memory) better than the Focal Spirit Pros and the Shures (which both strike me as more diffuse), and do not yet have the Oppos to compare them too. They're not as good as the VTGs or the Leatherheads (which both strike me as less diffuse).
They seal really well -- the earpad practically has my ear cut out of it perfectly, like they took an impression (when?!?!?). So these have become my new work phones.