Sweet-spot

Great insights and information. There are several ways to come at this issue. It seems that traditionally players and coaches are looking at strokes primarily from a max power perspective. In the Congruent System, I established evidence showing that players normally have an excess of power available, then submit that chasing power is not the best direction to approach technique issues. If players can accept the idea that technique is more about controlling the shot than powering the shot, then we can pursue technical methods that are willing to trade off minor amounts of 'top end' power or 'potential power', to pursue superior control functions. Interestingly, better control can lead to much better "usable or avg power" as a result.

In this case, it would seem that due to the superior power near the throat, we can get similar power levels with a less aggressive swing style. It would be interesting to have an app where we could input the factors to see the effect on power output. For instance, if we slowed the swing from 60 mph to 55 mph...contact at 23cm from the tip instead of 10cm and slowed the rotation around the handle from 2 to 1.5.....the idea would be that the cleaner contact at 55 mph swing and less RH rotation, combined with the more powerful contact area could register similar power levels at a far more repeatable level of execution.

And the final piece we need to complete the picture and gauge what stringbed area is preferable to make contact: how fast racquet rotates around contact, what's the difference between the velocities of tip, buttcap and everything in between? My brief analysis of single video of Kyle Edmund forehands (https://www.youtube.com/watch?v=5g3PjMKxVgs) provided data that coming into contact his racquet rotates around an axis at the bottom of the handle (moving axis) at rate of around 2 full revolution per second. And the difference betwen velocities of 15cm off the tip spot and 25cm off the tip spot comes at coefficient of over 1.06 (basis hand forward velocity included).

More data and more precise data required, but the general idea I stand for is 15cm from the tip might quite often produce bigger ball, particularly for more whippy strokes and slower incoming balls. Particularly on serving, I suppose, hitting closer to the throat will not be beneficial.

Counter-punching fast incoming balls should favor contact closer to the throat much more, returning first serves being an extreme example.

I have actually some personal experience with the matter. Recently switching racquets from Yonex EZONE DR98 to trial Head YOUTEK Radical MP, both modded to 352+g static weight, 333-5 kg/cm^2 swingweight, I initially got very jarring and erratic response from the Radical. Several sessions in, I've got video which exposed me hitting closer to the racquet tip. With my Yonex frames it was less of an issue thanks isometric hoop shape and thicker beam. Power drop is not that drastic moving up (lowish figures in the circles, thanks http://twu.tennis-warehouse.com/cgi-bin/comparepower.cgi):

With the new frame, making conscious effort to hit closer to the throat got immediate buff in solidness of contact and healthy spin... where we get to a new question: even though we can get higher power potential moving even closer to the throat, how will striking farther from the main strings' middle zone affect spin?

Based on the chart in the ACOR vs distance from tip, 15cm is already a decent spot (and it more or less matches the geometrical center of the stringbed, depending on the hoop length), but we should avoid striking closer to the tip. So "couple of inches closer to the throat" seems optimal for power, spin, and good margin against power drop, shanks or loss of control.