The NDI just looks and feels good. It's an AA done right. I happen to like the fact that it's regulated to a simlar level regardless of battery chemistry, nimh or li-ion.
I like mine a lot. I also removed the teeth. It was replaced with the Jet 1 Pro Version 3 but only because it was a lot brighter. I still like my NDI though. I may have a R4 put in it.