Very interesting thread. I always like seeing emperical data, because personal testimony (even mine) can be so varied since we all perceive things differently, and we are subject to a whole series of biases, something advertisers are all to willing to exploit.
In this case, from reading the replies, I think the issue here is with the definition of "Throttle Response." In one case, it's being used in a technical/mechanical/electronic sense, something that can be demonstrated with data and graphs, and in the other case it's a sensory/viceral/perception sense, how the bike now feels when twisting the throttle with a modifier between the grip and the ECU.
Because the term can be defined in either way, unless a definition of what "Throttle Response" is agreed upon, it can be hard to reconcile the two differing views. Both can be right, while remaining in conflict. I can see the difference in this thread and understand where each person is coming from.
Because we perceive reality based on the inputs of our senses, a change in a sensory input can equate with a change in perceived reality, such as the "feeling" of before and after, levels of power or acceleration. One thing I remember going way back into hot rod days, was how adding a loud muffler or exhaust can make a vehicle "feel" like it has more torque, horsepower, or acceleration. Place that same vehicle in a dyno, and you may discover the exhaust modification actually hurts overall performance. It would be very interesting to me to see a device like this dyno tested, although frankly it would likely be a lot of money spent for little practical return. For the consumer, if an add-on makes a vehicle respond in a more desirable manner, the reality of what it actually does in a technical sense, makes little to no difference. It can be as simple as: "I want the vehicle to do this, or feel this way." If an add-on succeeds in meeting customer demand, then it is a successful product.
I saw the reference to the Sprint Booster, which is what I thought about when I first saw the Pedalbox mentioned in this forum. The Sprint Boosters were also very popular with the Chrysler Crossfire community, of which, I was once a member. I recall very similar threads where a regular member of the forum raced, did a lot of custom performance and tuning work and would offer his analysis on various products, the Sprint Booster being one. He not only tested modifications on a dyno, he had the ability to get into the ECU/software side of things to actually watch what was happening. I always found the threads very interesting. Turns out the Sprint Booster did the same kind of thing as the PedalBox. It changed the rate at which the ECU saw throttle input. The car felt "sportier," even though it didn't change 0-60 or 1/4 mile times, increase top speed, horsepower or torque numbers.