You prolly don't need sway control in normal driving. however. should you need to dodge a deer, or some other sudden road hazard, a sway control bar comes in pretty handy.
Remember. Sway control is not meant to prevent sway. It is NOT anti sway. It is sway control. Sway control is only there to help stop /control sway once it has been induced by a sudden emergency maneuver. And you never know when that will happen. So balance the trailer. Makes sure it tows perfectly in NORMAL driving. Then add sway control, for those time when driving is not normal.