Didn't upadte the cube for a long time, it's in the middle of an overhaul. Still, I'm just implementing +1/+1 counters as a thing into my cube.
I think it really depends. Evo Sage looks strong because it will naturally go into a GW counters deck, and hitting land drops is never hard for green.
Now, what I find interesting: U is another colour that goes well into the +1/+1 counters theme, and
Flux Channeler still needs quite some work done to be effective. As a payoff, I find the Channeler to be worth a try in lower powered cubes, as it is certainly harder for those decks to cast a lot of instants and sorceries than hitting land drops, as this means using mana which usually also means that you won't develop your board further (except for proliferating).
Curse of Predation,
Thrummingbird and
Grateful Apparition are too consistent, that's true, and Evo Sage is nearly as consistent, but the Channeler seems about right I think. Will definitely try it.