: It is mostly useless in the ship on lower difficulties. I had to look up my
: Halo Anniversary guide to know that you need to keep the sniper with you
: on Legendary to stand a chance.
Keep in mind that normally the Sniper Rifle can only hold up to 24 extra rounds in your inventory. On Truth & Reconciliation, however, you start with upwards of 60 extra rounds in your inventory (though you can't pick up more until you run below the normal 24-round limit. There's a good reason for that - this level was designed for you to use the Sniper Rifle.
As for the Assault Rifle, it's worthless - just ditch it. Instead, use either the Plasma Rifle or the Plasma Pistol. If you have a quick enough trigger finger, I'd say use the Plasma Pistol, as it's more accurate, more flexible, has more ammo, and can be worked into a higher rate of fire than the Plasma Rifle.
Keep in mind, however, that I've never played this level on Legendary - even on Heroic it's surprisingly vicious, though I'm sure it's nowhere near as bad as on Legendary. Nevertheless, I know enough about this map to maintain that the Sniper Rifle is very useful here, while the Assault Rifle is next to useless, simply because it does not have the firepower to stand up to Elites.