I agree with most of what you state (thank you for the WoB quote btw, very consistent).
I kind of feel like the conclusion should be different, as from my point of view there will be much difference between T. and Rayse as Odium, the reason being his strong will not yet corrupted by the shard's power and, as Brandon stated, his fallibility as a "recent" mortal. If you think about it, we had T. as Odium for a few pages yet, and still he already managed in interfering with Hoid's plan (the depths of this disrupt is yet to be seen, but still an incredible feat), a thing Rayse could not do in thousands of years.
Either way, I am so thrilled to uncover T.'s future plans. Him being not only a powerful god but also a man with a strong philosophy, the exact counterpart of Dalinar's, these are the things that makes a story interesting.