I'm unimpressed with the Aggradon ability in general. Maybe now that units of 6 are a thing, it will bear more fruit?
The Aggradon Primal Rage ability was pretty lackluster when the battletome came out. But the change to coherency rules changed Aggradons from a blah unit to a great one. It changed the Scar-Vet on Aggradon from pretty useless to very useful in the right list. A reinforced unit of Aggradons can be very impactful in either faction.
I think Primal Rage will be somewhat better now. I don't know how often it will get activated without the Scar-Vet, but its potency when active is undeniable.
Let's look at some average numbers. I'm going to use Lancers with Clubs for this. They tend to be slightly better than spears against all but the highest save values (3+ save is the break-even for unbuffed Aggradons).
(Sorry for the long, yet not exhaustive list that follows.)
A unit of 6 Aggradons with Clubs will deal a base damage, without any buffs, of 19.0 wounds against a 4+ save. That's not a bad start.
With Rage 1 from staying in combat or a Scar-Vet on Aggradon: 23.4 wounds
Koatl's Claw Aggradons on the charge: 23.7 wounds.
Starborne Aggradons with All Out Attack: 23.7 wounds. Maybe from a 7" teleport with +1 to charge.
Koatl's Claw Aggradons on the charge with Rage 1: 29.3 wounds. Even against a 3+ save, they still deal 23.0 wounds.
Koatl's Claw Aggradons on the charge with Empowered Celestite: 25.5 wounds.
Starborne Aggradons with Rage 1 and Serpent Staff: 28.2 wounds.
Starborne Aggradons with Serpents Staff and All Out Attack: 28.8 wounds.
Starborne Aggradons with Rage 1 and All Out Attack: 29.3 wounds.
Koatl's Claw Aggradons on the charge with All Out Attack: 29.6 wounds.
Koatl's Claw Aggradons on the charge with Empowered Celestite and All Out Attack: 31.8 wounds.
Koatl's Claw Aggradons on the charge with All Out Attack and Serpent Staff: 34.8 wounds.
Starborne Aggradons with Rage 1, All Out Attack and Serpent Staff: 35.2 wounds.
Koatl's Claw Aggradons on the charge with Rage 1 and All Out Attack: 36.57 wounds.
Koatl's Claw Aggradons on the charge with Empowered Celestite, Serpent Staff and All Out Attack: 37.0 wounds.
Koatl's Claw Aggradons on the charge with Empowered Celestite, All Out Attack and Rage 1: 38.8 wounds.
Koatl's Claw Aggradons on the charge with Empowered Celestite, All Out Attack, Serpent Staff and Rage 1: 44.8 wounds. This one is extreme, I know, but it's still dealing an average of 29.2 wounds against a 2+ save! Not much can survive that.
Note that I never bothered to add in Rage 2 or 3, as they are probably quite improbable. But if you get them, yikes! The last one on the list, but with Rage 3 yields 60.3 wounds against a 4+ save, or 39.2 wounds against a 2+ save.
And I didn't include Hoarfrost (because the Seraphon calculator I made doesn't support it yet), but theirs a lot of bugging potential there, even for Starborne.