My take on all of this....from an admitted hack.
There are undoubtedly differences in equipment, such that one brand or style is capable of performing better than another. The level or amount of difference will vary, depending on the skill and ability of the person using said equipment. As I said, I'm a hack, anything that helps, if even a little, is magnified much more than the difference it might make for an A player, or better.
That having been said, the equipment itself doesn't make a persons game better, it merely helps keep the mistakes smaller in effect, perhaps a little more margin for error....
I truly believe that there is another effect as well. I hate to use the term "placebo" as that places a negative connotation to the discussion, perhaps "confidence" is a better way to describe it. If you feel more confident and comfortable using something that is purported to perform at a higher level, then your game should be better as well. We all play better when we play with confidence.
I truly believe that the real bottom line lies somewhere between where Chris and Dr. Dave are coming from. The practical, real-world application, if you will. Dr. Dave is working from a clinical, objective point of view, and likely with a level of skepticalness. (Necessary, I'm sure, from a scientific point of view.) Chris has done a lot of research and development, not just in the area of chalk, but in all his pool products. He gets feedback from players (I've been fortunate to be able to try some of his products as they were being developed, a fun process) and is truly enthusiastic about what he is doing. I always look forward to what he's going to bring to market next. He is good for our game, developing new "stuff" and providing it from the little guy, not a big company.
I haven't given Great White a test myself yet. I have a piece in the bag, I'm waiting until I finish my current cube of Magic Chalk to try it. I don't play often enough (or well enough, probably) to try a side by side comparison. I want to use one regularly, and make my impressions after that.
I had been using Predator previously, which I liked pretty well. I like the Magic Chalk more, if only because it gets FAR less on my hands than the Predator (the biggest issue I have with Predator). With both of those chalks, I get the feeling that I get a little better grip on shots involving spin, primarily low left or low right. That may very well be me doing a better job with the stroke on a given shot, and that using Masters I may very well get the same result. Still, it "feels" better to me, so I will continue to use it. For the cost of their chalk, and how long it lasts me, that's not outrageous in the least.
I love how the discussion will always come around to the .15 someone pays for Masters, and how crazy it is to pay more for chalk. A couple of bucks for Great While, Magic or Predator isn't terribly frivolous. Probably many of those folks making that complaint are playing with a cue that costs hundreds or even thousands of dollars, stored in a case that is another several hundred dollars, which contains a break cue and maybe a jump cue, again costing significant dollars. Yet those same folks will poo-poo a couple bucks for chalk to use with all that cool equipment? (I do draw the line at Kamui, and it's price vs performance/challenges tho.)
I wish Chris (and RJ, with Magic) all the best, and hope they are wildly successful.