Well.. Umm, Er... You see, circumstances have prevented me from getting much use from it yet. I have it set up for standard 1 1/4" eyepieces. It didn't come with a diagonal or provision to use one. I had to get an adapter made to be able to use anything, So I chose to get one for 1 1/4" accessories. Interestingly enough, the one Derek linked to (owned by SteveMM), was also missing any provision for using a diagonal. Steve had to get an adapter made too.
I've had mine for going on a year now. The person I bought it from said he acquired it from the original owner, who brought it here from Japan. He said he lost contact with the owner, which I suppose means he didn't want to tell the guy that he flipped it for a quick buck.
I don't know if your Nikon has the same circular opening (~43mm) that my scope has, but if so I am going to have PreciseParts add it to their database so people will be able to buy an adapter. It sounds like you can already observe with yours. When you do, in addition to telling us how nice the views are, could you see if there is color in focus and out of focus on Sirius? If there is ED glass in the scope at f/15, there should not be significant color out of focus, whereas a standard achromat (even one as well corrected as a Nikon) should have a small amount in focus and a mild amount out of focus. That will hopefully settle the issue of whether the scope has ED glass or not.
Also, I am interested in how the mount works, specifically how stable it is.
Yes sir, I will do that.