maybe the pure-data API lacks functions for saving/restoring state of *ANY* external (if the externals needs/wants this)?
you can 'fudge' it by recording the last incoming message per-selector, or the last message coming out of an outlet, with a figure-8 looped abstraction and [pool,pdcontainer,coll]. or wrap an object directly a GOP with store/load state buttons..
i do think a proper addition to the API for reflection on the current state, and subscription to update notifications, is essential however. not only for real state-saving, but for those who want to (easily) make non-Tk GUIs for only a single object, or an entire or several patches...