I really see no point in roughing up the inside of the barrel, the insert will cover most of the wall of the barrel so it would not have an effect on the sound. The density of the wood that is used in the insert will be more of the controlling factor than the density of the wood used in the barrel. An insert made of a soft wood will produce a muffled sound, while a hard wood will be more crisp and the acrylic or plastic insert will produce a sound that is crisper than most wood inserts.
The reed is another issue, in today's duck calls the reeds are usually 10 mil Mylar rarely one will see a different thickness. And in some cases also very rare you will see old style calls with metal reeds. The length of the reed determines the sound and the length of the tone channel will determine the length of the reed. It takes all of the pieces and parts in the right combination to make a good duck call.
The barrel, since the duck caller will have his hand wrapped around the barrel when in use the to thin could muffle the sound. The best thing to do is to give a good finish to the inside. Finishes, both inside and outside make and break duck calls. Duck hunter get out in the nastiest weather, cold, rain, snow nothing seems to bother the the true duck hunter.