Since nobody else has commented on this, I will take a stab at it. This is what I have found, generally speaking, but I will preface my remarks by stating that, in my opinion, there are so many variables involved in call making that it is hard to make statements as absolutes. I will also say that I don't consider myself to be an expert on all of this, by any means,....just stating what I have found in my call-making experimentation and use.
1) Uncut calls give you a clearer sound, both front and back end, but generally lack the rasp that most experienced mouth call users desire.
2) In my experience, stretching the latex tighter usually results in a higher pitched call and often makes the break-over from high to low sounds more difficult, but also depends on the cut design.
3) Close stacking of reeds, in effect, negates the whole purpose of having multiple reeds in calls. They will begin to function as a single reed when the reed layers are not spaced far enough apart to allow for the proper individual reed vibration;
4) I'm sure back tension in certain calls is an important factor, but that is not the case in all calls. I have made many calls that work just fine without putting in any back tension;
5) Rasp in a call is generally increased, and tone lowered, by depth of cut of the sound reed,...up to a point; after that point is reached the sound of the call will begin to deaden if you deepen the cuts more; deep cuts also have a tendency to begin folding over and sticking, resulting in a total loss of sound quality and control;
6) Some people swear by the thicker latex, but I have not found a call design using anything larger than .003 that I personally like the sound of better than calls made from .003 and/or proph;
