I think the good doctor is right on. We've also experimented with different levels of acceleration from rest and there's definitely a sweet spot at what I'd consider "moderate" acceleration. Stomping on it wastes fuel for sure, but accelerating too gently (unless it's SO gently as to never leave E-mode) tends to use just the ICE to do the work, and uses it longer.

Watch the power distribution and instantaneous mpg displays. At moderate acceleration, both the ICE and MG are used, and the instantaneous mpg is about the same as for gentle acceleration, but you have to do it for less time until up to speed, so less fuel is consumed. We've been using this technique since the last half of our previous tank. That one was the best tank mpg to date (around 39 mpg). The current tank is even better, around 41 mpg so far (indicated), but it's not time to fill up yet, so I can't quite declare that as a tank average.

It's pretty cool that great economy can be had without dedicated hypermiling techniques.