Howdy dpharmd07, and welcome to CPF,
Gee, your first post is about buying a NovaTac 120P. Cooool. Yep, I carry mine every day.... so I will give a big +1 to what everybody has said so far..... guilt free lumens is the way to go..... I just change out my rechargeable once a week or so, pop in a fresh one, and I'm ready to go.
BTW, I prefer to use protected cells.... and since the NovaTac seems to handle them ok (it goes thru the complete step down cycle without the battery's protection circuit kicking in, so it won't just go off and leave you in the dark), there is no reason to use the unprotected kind.
You should spend a bit of time in the 'Batteries included' section of CPF to get a better understanding of what cells perform best, and what kind of charger to buy (one with individual charging channels)
And like yaesumofo, I keep 6-8 CR123 primary cells around 'just in case'. Enjoy your new light.