I didn't put much effort in my bred and flawed lvl 220 Argy but turns out he easily kills a lvl50 Giga while I skilled mainly on stamina and weight. The Statgains per lvl are so strong he still has 6k health and 1000% dmg. There is no challenge anymore when I fly with him through the map. Perfect to get prime meat for taming.
Getting a massive TLC update in March 2018. The saddle will act as a mobile smithy, Argentavis will be able to carry with Talons as well as with its beak, reduced carry weight on obsidian and a few other unannounced resources (similar to the mammoth and wood), and will also gain a Rapid HP Regen upon eating (likely from devouring corpses and not specifically food from inventory). Like so people can see!