Honestly, it boils down to how well you feel you're doing in your current build. Are you struggling to kill things, or breezing through dungeons? And what difficulty are you running?
The main appeal of Primal Avatar is Balanced Attacks, which knocks folks down on vorpal melee strikes. This isn't actually half bad for a Tempest ranger. Since it's a tier 3 ability, you'd spend at least half your time in PA using that.
Strimtom also has a
Tempest build - while specifically for Aasimar, you could swap a few feats around (IC: Slashing instead of bludgeoning, for example) as you see fit.
Alternatively if you have a few siberys dragonshards, you could do a few feat swaps, respec your enhancements and gain 2m xp in a slightly sub-optimal version of his build. But that's going to depend on what dungeon difficulty, gear, etc that you have