Ideally you want your lower back to be pretty flat.

Right now you've still got a good amount of curve so it makes it look like you're fighting the saddle. You're rotated a lot further forward than you would be on a road bike, but you're still pretty far back for tri.

That bike doesn't look too bad for you, but as you rotate forward you're going to need more length, which the P3 or IA10 would give you compared to the Shiv. I went through the same thing with my fit.

I really appreciate the feedback. Would you say that the best setup of the 3 is the last one (in the garage)? I'm going to try and ride that for a few hours this weekend to see how it feels.