Sated Devourer is definitely stronger. However, runic echoes gives a giant power spike a lot earlier than you can hit sated. The mana regen, movespeed, and extra aoe clear speed make it better than warrior.
This is a very good meta for Udyr. He has a lot of synergy with the current jungle items, good split pushing, tankiness, and high chase potential with cc mixed into his chase tool (This is mostly because deadmans + swifties negate his old weakness to kiting for the most part).
It doesn't help that a lot of the harder matchups for Udyr aren't really being used. I mean it was a different story during that long period where every game had Sejuani, Maokai, Malphite, Skarner, Sion, and cc heavy juggernaut / tank comps. His weakness is team comps that don't let him anywhere near something squishy. Chain cc, snares, disengage, and tanks are all annoying for Udyr. Not to mention he's rather lackluster in teamfights when even or behind. (Hard to do generally Udyr will be 1 - 4 levels ahead of the enemy)