Define smooth? Consistent lbs./inch draw length, say like 3 lbs./inch out to 29" or 30"? Or maybe you mean something else? "Smooth" is kind of ambiguous, everyone here uses it but I wonder if they all mean the same thing?
Re: lbs/inch, whether TD or one piece it would have to do with the limb design and its profile unbraced, braced and drawn to your desired draw length. Many other factors as well but basically you can arrive at the same end with either one piece or TD.
There are more overt factors for deciding whether you want a one piece or TD i.e. do you want to have a second set of limbs, carry it in 30" case etc.
I chose not to answer your poll as I considered it irrelevant.
Kris