RNG/WAR is a cheaper and less effective way to play ranger. Can you get away with it? Probably.
But why are you a ranger if all you can afford is to be the cheaper and less effective you?
RNG/WAR cannot pull as safely as RNG/NIN, due to the lack of Utsusemi.
RNG/WAR will never be as accurate as RNG/NIN, due to the loss of a small AGI bonus and the ability to equip a second Archer's/Hawker's knife, or the mighty Francesca!
RNG/WAR uses berserk to hit harder per-hit than RNG/NIN, meaning you get to fire less and save money. Sounds nice on paper, but in reality, it becomes much harder to control the ammount of hate you give yourself while still dealing damage.
RNG/WAR only has Defender to fall back on once every five minutes should agro turn his way. RNG/NIN gets to avoid 3 hits for free every 30 seconds. There is no debate as to which option is better for both you and your party.
RNG/WAR isnt as gimpy as RNG/THF, or RNG/BST, but its seriously lacking when compared to RNG/NIN.
If your only arguement is that you are already accurate enough, then you dont have Sidewinder/SlugShot yet.