Sure, {co'a} is often enough, and I use it a lot myself. It just lacks the sense of transformation that I get from {binxo}.
I would say that {ro nu binxo lo ka broda cu nu co'a broda .i ku'i na ku ro nu co'a broda cu nu binxo lo ka broda}. That is, to me, {binxo} is about an experiencer undergoing a change (where experiencer should be understood loosely in the thematic role sense. Certainly a binxo1 need not be sentient); it is making a claim specifically about the binxo1. {co'a} on the other hand just says that some event starts to occur, with no focus on any of its parts. That's why I don't consider them the same, but as I said, {co'a} is always true when {binxo} is, though not vice-versa. The difference is often subtle or completely invisible, but sometimes it isn't.