Spelling is the least of my concerns, as a boy, when the whole ninja craze came around, it was spelled either way, later in an attempt to split hairs and seek legitimacy and seperation, people began emphasizing the ju spelling in pompous fashion.
original ninja were men of little means and were by nature pragmatic guerillas skilled in asymmetric warfare. The closest thing to anyone training in the modern equivalent of ninjJItsu, are the various special forces operators. They are the truest practicioners of the concepts of ninjitsu today.
I myself am a combat veteran of two deployments to Iraq. My unarmed combat experience includes training in modern army combatives, competition experience in BJJ, Judo, and Shingitai JiuJitsu, and training in kickboxing.
My Kug Maky Ung system of ninjitsu will emphasize modern weaponry such as combat pistol and long range shooting, as well as knife and club.Some traditional weaponry will be trained, mostly to satisfy my sons' interests.
I have self studied from various bujinkan and koga resources and feel well qualified to synthesize my own ninJItsu ryu and make it my family art. Our training sessions have thus far been so fun for my kids that they dont even realize they are working hard.