From what I've found playing with Saki vs Saki AI, is that regular Saki sounds way more synthetic as a default without lowering or tweaking any parameters at first, while Saki AI sounds kind of rough if you use the same kind and amount of parameter tweaks. With default Saki (and all non-ai synth v banks I suppose), you sort of have to "shave" the synthetic throatiness away by lowering the tension on certain phrases, and making use of the other breath and gender parameters, but in return, you can do so much more with her regular voice. You can make her tense, whispery, robotic, or cute, while Saki AI has troubles covering these singing styles as well.
(not to plug my own stuff but)
I made this cover to kind of demonstrate how regular Saki can sound like if you really edit her tension heavily. I think she sounds like a good halfway point between her default unedited voice and her ai voice.. The way I see her two voicebanks, is Saki regular is like having a big piece of marble you can sculpt into many things yourself, and Saki AI is the human looking statue that's already been premade and doesn't leave much for any other interpretation.
I went back to this SVP file after Saki AI came out, and plugged her into this just to see, and yeah, she actually sounded kind of terrible with the edits made for regular Saki..
Overall I'm glad we have both though, love Saki.. And who knows what the future holds, this is our very first AI voicebank released for SynthV after all..