Ok here is my answer to the question....
Pressing is based on the willow.... If you have a piece of willow with lots of grains on it then you'd press the cleft lighter... Why because the grains will already add a certain amount of rigidity / stiffness and therefore it doesnt require the same pressue. A loose [only a few] grains will require more pressure as you don't have the stiffness you need
a lightly pressed bat in any of those scenarios will not give you extra peformance you'd get a dull thud and a dent....
Ok that all said a lightly pressed bat if done properly will give you ping and if anyone can work what I'm getting at here I should really offer them a prize...
Now I'm going to talk about sound.... If you are lucky enough to have a bat that is in your opinion a pinging machine... Hit it with a mallet and listen then get another bat, if you can, that isn't quite there and hit it and listen. note the difference in the sound, there is a difference...! If that isn't an option or you are ballsy enough go to a shop with a mallet and pick out a top of range Newbery or Salix [slightly bowed if possible] tap them with a mallet listen and pick out a bat that has gone through a product line note the difference.... The sound difference is related to vibration [energy loss] and therefore ping...
I doubt that made a huge amount of sense but was a good advert for Newbery and Salix's press