Lorenz' review has an excellent discussion of (what I have called) Change 2, which includes this paragraph:
The diachronic program of Plato's Utopia Recast, with its prominent claim that Plato abandoned tripartition of the soul, depends significantly on its view of what tripartition comes to. If that view is in large part mistaken, as I think it is, this damages much of the diachronic program. If, for instance, tripartion never involved three sources of rational agency, this defeats one of Bobonich's better reasons for thinking that Plato abandoned it some time after the Republic. The Timaeus explicitly denies the capacity for reasoning to the soul's lowest part (Tim. 77B3-6). On Bobonich's view, this is a devastating blow to tripartition. (317-8, cf. 296-7). If, however, the non-rational soul parts of the Republic are already conceived of as incapable of reasoning, the Timaeus simply makes fully explicit what has been assumed all along.Lorenz's concerns about Change 2 seem analogous to those I have been raising about Change 1. (Strangely, in my view, both Lorenz and Rowe, in their reviews, seem to grant without argument Bobonich's construction of Change 1.)
The review (q.v.) also includes an effective criticism of how Bobonich attempts to deal with Timaeus' affirmation of a tripartite soul. I've decided that I won't post on that after all, since I couldn't say any better what Lorenz says there.