Another interesting thread, as always it all comes down to scientific measurement differences vs functional differences.
Functional differences will always be the ones that matter in the game, even though the scientific measurements behind them are not so different between each shot.
That, along with the facts of lackness of absolute repeatability and scientific limits in measuring all factors involved in a human action, brings the whole matter down to the way of approaching it.
Anything thay will bring a different result, no matter how, matters. That has nothing to do with measurement differences which may not be that significant, one does not contradict the other.
As far as chalk is concerned, apart from all points that already are mentioned by others, I would like to add a simple fact that has been known for years, If I missed it between all replies please ignore it: players usually hang to the same chalk during a match, even using their own. If by mistake you mix different chalks when playing, general experience shows you usually end up with a miscue, even if they are of the same brand.
I use mainly Blue diamond chalk, I find the tip grip-CB chalk mark balance it has good, with good consistency between chalk cubes, usually better than chalk you come up against in pool halls.
Last year I bought some supplies for my home table, among them was a "regular" chalk brand for trying which looked nice, only to be totally dissapointing upon use. That chalk just refused to stay on the tip...
I recently played in a tournament in which tables were not covered with Simonis cloth, that cloth seemed to have more nylon substance than Simonis, me and other players noticed that the CB would tend to swerve less than expected in slow to medium low side spin shots when trying to "kill" the CB, ending up in more missed shots, usuallly on the "thick" side. I changed after my first match to kamui chalk and it did seem to help, I can't ignore that in these cases a placebo effect takes place into a player's mind, but sometimes when things do not "fall in" you just have to change something, anything, even the slightest thing with the slightest technical difference, in order to "stay there"...
Petros