DriftyGames is unfortunately making it a challenge to experience everything in one playthrough with all the decision points in this project.
I have not experienced all of this project as of this point, as I am trying to go about it Pokémon style!
(Collect them all in the Harem!)
Contrary to the name starting on the Brawls side seem to be the big brain decision regarding talents, which is slightly odd...
Here is why:
Starting from the Brains start node I seem to only be able to unlock the neutral node and the three nodes connected to the Brains starting node.
But starting on the Brawls side instead it is possible to unlock almost everything, except the Brains start node and the three nodes connected to it.
The ? nodes at the top seem inaccessible, at least for now. 1 point is removed if you try to unlock them, but cost for them is stated to be 3 pts.
Look in the spoilers for image documentation.
So the big brains start is the brawls side! An even bigger brains start is to also use the URM mod to negate not having the Business Man node, the Effective node, and possibly the Sweet Talker node as well!