The DT-250 250 was my solution to the need for "closed Senns" (in my case 580s) and I'm sticking with it. My vague, perceived frequency response for the two is quite similar. If you find those other closed cans too bright or forward you'll probably like these. The fit/feel is also similar, unless you have a big head or big ears.
There is a major difference in sound: I'd say the soundstage is quite narrow relative to Senns, regardless of the amplification. As a result, you lose a bit of clarity and air, and complex passages can get a bit congested. Maybe not the best for really critical listening, but they are very enjoyable, and do take full advantage of the best amplification you can provide (I guess if you're using the Grace you should be fine with pretty much anything).
I have not heard the CD-3000 (except at the WOH tour a long time ago, which I didn't like but later heard rumors that there was something wrong with that pair or something). Other closed phones I'm familiar with are the W100, ER-6, and (fading from memory though) CD-1700.