“Open Theism and Other Models of Divine Providence”:
As a group, open theists are committed to a robust perfect being theology according to which God is conceived of as a metaphysically necessary being who essentially exemplifies a maximally excellent set of compossible great-making properties, including maximal power, knowledge, and goodness. The differences between open and non-open theists (both classical and process) have to do with what that maximal property set consists in, not with whether God exemplifies such a set.
God is Open 
I think Rhoda extrapolates too liberally outside the confines of his own philosophical background in applying his exposition of “perfect being theology”. Not that there is anything thematically incorrect with ascribing “maximal excellence” to God. :) Only that it is not true that open theists in anything that approximates a majority talks like that about God. While the theoretical schemata may exist in elementary or kernel form ‘a priori’, very few open theist would claim to have been acquainted with Rhoda’s “dictum” never mind resort to them as “first principles” as it were.
Is it worthwhile getting acquainted with such terms? I suppose. But I think most open theists, being theists first of all gravitate towards using Biblical patterns for ascribing “greatness to their Creator.” I.E., God is love, and God is light in whom there is no shadow of turning, phrases that form more easily recognizable constructs that are consistently worked out through out the Bible.