They may be a method of assessment for a personal view of truth. However, I hold that as different from "Truth" (with a capital "T", a universal truth).
Ah, therein lies the rub! A fundamental view of Epicureans is that there is no universal Truth. Or to put it another way, the universal truth is that we live in a material universe with no supernatural god(s) and no afterlife. Much of Epicurus' thinking was in response to, and a refutation of, Platonic forms and ideals. Since he posited that there is nothing other than atoms and void, an idea floating around in their midst would be tantamount to the mind being located in a mist floating around outside of the body.
The Stoics believed in a universal logos: an intelligent universe. That was one of the fundamental differences between them and the Epicureans. You can find Marcus Aurelius pondering this in his Meditations. Interestingly, the modern Stoics seem to have largely stepped away from this idea. An interesting treatment of the conflict is in Cicero's On the Nature of the Gods, a book which introduced me to the Epicurean position and convinced me of the fallacy of the logos (which result would have been much to Cicero's horror).
For some reason this brings to mind the book Zen and the Art of Motorcycle Maintenance, in which the author and protagonist gradually goes mad in a search for a universal Quality. He was vainly trying to define something that doesn't exist. The admittedly difficult issue that must be dealt with on a personal level is whether one believes that there is no Truth out there, or whether there is one that we as yet are unable to fathom.