I started down this path too, but I couldn't get Creo to make all the individual boundary blends and make them tangent. Were you able to do so?
Doug; under the tabs in the dialog, there is a place you can set the state of the edges. You get free, normal, tangent and curvature.
You can also click on the white bubble with the black dots in the graphics window. In the dialog, you can set of change the feature you want Normal, tangency, or curvature from.
And you can also assign you own connecting points. Boundary blend is simply full of little Easter eggs.
I'm familiar with the controls, what I meant was that when I set them to be either tangent to the adjacent surface or normal to the plane the curve was sketched on, Creo refused to build them Some of them refused to build at all because it said the corners were not joined, even though the curves were defined as aligned to one another. Thinking about it again, I believe I was using normal to the sketch plane and that wasn't necessarily true, since I wasn't building a fully symmetric part.
Unfortunately, I didn't save that version with the additional curves. Maybe I'll go back to the one I built with the N-sided patch and try again if I have time.
For what it is worth, here is my attempt at modelling the required part (done with the N-sided patch).
Tried creating all the curves and creating the 6 boundary blends again, Creo would not accept tangency at the central transition curves. It must be how I'm creating the transition curves, but I've got no more time to play with it right now. I've attached the model in case anyone wants to have a look.
Nice! I have only had to use it a couple times, but it worked excellent, if the interface is a little clunky. Your curvature looks great. I used it on my tri-y surf.