EDITED: I speak only for PvP
I was main soulbeast for years and I think the Untamed outperforms the soubeast. I am using LB and GS.
A soulbeast has a burst every 60 with One Wolf Pack and 30 with Sic em. An untamed has sustained damage every 15 secs and teleport to chase/finish your enemy.
Soulbeast needs to activate many utility skills to be effective with a burst. You lose the burst If the enemy blocks, get invulnerability, dodge, etc.
Untamed has more survivability, because it can block projectiles, get 15% more defense on pet unleashed, more vitality. A soulbeast cannot step into a team fight without risking being targeted. Soulbeasts mostly uses berserker an scholar.
Untamed can chase enemies even behind walls. Fighting as a Soulbeast, enemies can just hide behind a wall making you to waste your burst. Line of sight is one of the best methods to avoid the Sic Em combo.
I think the play-style is just different. Soulbeast DPS is like a thief waiting for the right moment to kill. On the other hand, Untamed can be played like a Rev. You can wear down your opponents with constant damage and then activate your melee combo (teleport + pet swap +F skill + GS2 + GS5 + unleash pet + F2 + F1 + Unleash ranger + GS1).