Hello, "TObj" is rarely used nowadays. I even thought to mark it debracated.
CAF and its childs are ready to work with TStdDoc_Document, labels and nodes, attributes,...
Undo/Redo is a main OCAF's attribute functionality. These attributes are used for both of your formats. I really recommend to use basic implementation of OCAF attributes and work around it. As for a XCAF, it has some attributes, but I do not recommend to build application around. And even more then that, you can apply your own visualisation logic on both of them and easily import data from DE on both formats or own format.
If you want consulting about application architecture around CAF, you can use our commercial service (see CAD consulting services | CAM consulting engineers)
As for a CAM, we have a multiple projects, where OCAF used as a application kernel (path tracing, geometry detecting, collising detecting, feature recognition, recompulating, manipulation, scaling and any other possible functionality around 2D and 3D are possible with pure OCAF).
Best regards, Commenter-1.