To start, you wont be feeding the mob as much TP with RNG.

RNG has more ranged accuracy, and seeing as how Sidewinder is a low accuracy WS, SAM will miss a LOT compared to RNG.

RNG gets Eurytos' Bow. Sam gets War Bow.

RNG gets to stay back and get the distance damage bonus.

the drawback is, you use a lot of ammo.