Your suggestions are remarkable, but it'll take time to learn customizing the system from the core to extjs to obtain exactly what we need. MODx's steep learning curve is not really at the way using its template or other elements, but advanced customization. (Maybe it's time for me to take higher steps

).
My previous ideas are not new ideas at all, while I can see them have been done in ProcessWire (this CMS inherited many things from MODx, I think), it has a resource tree with pagination (if I'm not missing somewhere).
Sorry for pointing other CMS in the topic, but it's worth us taking a glance at. Pardon me, I'm not trying to convince our MODx developers to rework on the tree or somewhat, just a little attention about how to organize your resources and usage of resource tree that would make it more effective.
Otherwise, I think Articles can be a great extension to start digging, because it creates new resource container and doesnt mess the tree up.
One problem always comes to me, that, there're too many ways to achieve a purpose in MODx.