The Divine Soul sorcerer (Xanathar's Guide to Everything, p. 50) gets the Empowered Healing feature at 6th level:
Starting at 6th level, the divine energy coursing through you can empower healing spells. Whenever you or an ally within 5 feet of you rolls dice to determine the number of hit points a spell restores, you can spend 1 sorcery point to reroll any number of those dice once, provided you aren’t incapacitated. You can use this feature only once per turn.
However, the version of the Favored Soul sorcerer (the original name for the subclass) in the Modifying Classes Unearthed Arcana got Extra Attack at 6th level instead:
Beginning at 6th level, you can attack twice, instead of once, whenever you take the Attack action on your turn.
Compared to a College of Swords/College of Valor bard or a Bladesinging wizard, is a 6th level Sorcerer with the Extra Attack feature balanced?