As the prebuilt dCore section is very static but for kernel module updates, I think we are ok to place /usr/bin ahead of /usr/local. Any possible file collisions in the future, the burden will be on the prebuilt section not to collide. Any packages in Debian that need to be superceded by prebuilt, that can be done by blocking the Debian package and/or uploading a prebuilt one as prebuilt is found first by design ahead of any DEBINX, so the /usr/local path precedence is not needed. Apps like fltk editor can have a .desktop file to allow them to easily be launched by menu.
If this sounds agreeable, will apply on next RC.