I've EDC the NDI since nitecores original thread offering the NDI's for special sale...
-I can say the strobe probably isn't effective tactically since it's rather slow.
-The knurling isn't quite as aggressive as it could be, but far better than solarforce products.
-It's a bit longer than the D10
The reason I bought it was it's incredible multi-cell capability and it's compactness--at the time of release it was the most compact forward clicky AA light available, the the only one able to regulate on 14500 cells.
HOWEVER, I believe the D10 will be superior now, because it uses a processor to regulate the voltage and output. The NDI had great regulation on 14500 and it had AA Alkaline capability but the Alkaline and NiMH regulation weren't nearly as good. The D10 will regulate very evenly throughout the battery's runtime.
One nice thing about the NDI was dual modes. Basically you have tactical level brightness, which is useful if you have a house invader for example. The second mode, which is user definable is best for either medium or--my personal favorite--really low. I used the really low setting when I was an LP to investigate shoplifters deep pockets/cavernous purses etc. because I didn't want the beam to bounce back up and blind me.
Good luck!