Problem is, OpenCog (and SOAR, too, when I saw it) is still based in a fundamentally certainty-based way of looking at AI tasks, rather than one focused on probability and optimization.

Uh, what were you looking at? The basic foundation of OpenCog is a probabilistic logic called PLN (the wrong one to be using, IMHO, but a probabilistic logic nonetheless). Everything in OpenCog is expressed and reasoned about in probabilities.