Aiki is one of those things I try not to think about too much. It is clear that even in one educational generation, Takeda to Ueshiba, there is a great change in how the term is used and what the term is supposed to encompass. It's also pretty clear that Ueshiba expressed and talked about aiki in different ways throughout his career. What this means is that there are a whole lot of different ideas out there about what aiki is, and I think it would be a pretty presumptuous and largely fruitless endeavor for me to try to decide which one is "right".
I'd much rather spend my time trying to figure out what good aikido is; that's nebulous enough without trying to grab hold of a concept so broad and so varied in interpretation as aiki.
Most of the change in how the term is used came from Kisshomaru, rather than Morihei. If you look at what Morihei actually said it's not incompatible or even inconsistent with what comes from Takeda via the Daito-ryu lineages, and it doesn't really change from 1933 to the late 1960's, although it's clear that he gives various methods of explanation.
I'm curious as to how one can figure out what good "Aikido" is without the "Aiki", wouldn't that just leave "do"?