Krestin,
In my limited experience with all black finishes I believe it is the most difficult to replicate. I personally use many subtle shade or tone differences as I move around the model. Different blacks for example interior, Nato, Semi-gloss, and all with slight tinting with brown, grey or green in the enamels I use provide a bit of contrast and break up the monotone effect. If you check out some of the photos in Completed Models Sept. 2012 of Albatros DV "Monnington" you can probably see the effect.
Good luck with this one, great scheme you've chosen.
Cheers,
Lance