If for some reason this ever gets implemented, you should not be able to exert any suppression on the enemy while doing it. It's the fanatical yelling and swarming as a horde which makes a banzai charge scary.
Come on, banzai wouldn't be awesome without the yelling.
Yesterday I ran towards the beach as a jap SL with my sword, killed an american, and just ran back to my ranks without taking any damage. I know it was a stupid thing to do, but it was just so awesome.
Anyway, it's not like most people care about the yelling... also yesterday I killed 5 or 6 americans, and most didn't even bother to look at me and I would just stab them in the back one by one.
Have to agree with most of the guys who say that the Banzai wasn't a stealth tactic, hence being silent doesn't make much sense. The whole point was to intimidate the enemy while performing a suicidal charge.
The practice of sprinting and then holding down your melee weapon just before getting to your target makes the most sense. In this regard, you are effectively rushing an enemy position (and praying your avatar doesn't spout off Japanese non-sense to give away your position) before attempting to eliminate the opposition. Then again, a group of Japanese charging through the jungle with their bayonets prepped for use (i.e. sprinting with mmb held down) would be terrifying for the lone GI watching that section of the jungle.