I realize that I am new here but this seems like a whole lot of 'voodoo magic' to me.
The physics of this are very simple. The object to achieve maximum spin (at any tip position) is to have the largest contact patch between tip and cue ball. This means that given tip placement, the optimal shape is one that allows this to occur.
Meaning if you are at the extreme edges of the cue ball, a more rounded tip (and smaller diameter one as well) will get better contact. If you are closer to a center hit, a flatter tip (and larger diameter tip) will get more contact...and thus more spin.
If I had to take a guess, and this is simply my opinion so please keep your flames to yourself, is that people like the amazing Mr. Reyes is that he rarely has to resort to extreme edges of the cue ball to make position. It does not take a genius to realize that adding spin to a cue ball is a variable. The more extreme the spin, the larger the variable. Why take the risk?
In any case, the best tip shape is the one that works for you and your game so why freaking argue over it?
Personally, I prefer a more rounded tip, and a smaller diameter one. Not because it makes me magic, or elitist, or super-special...but because *I FEEL* that the smaller diameter of the tip allows me to be more precise with my tip position when hitting the cue ball. Is this true? I DON'T CARE! It gives me confidence to shoot this way, and confidence is the one thing that matters a hell of a lot more than your freaking tip shape.