No argument, I understand how new tools can help you learn from the feedback they provide. And early on in my pool journey I used some of them, and they helped. But the benefit, at least for me, was miniscule. What I use to measure where my stroke is at including accuracy of hit on the cue ball, speed, feel, everything really, is the simple drill of place the cue ball on the spot and bank it back from the far short rail. If it comes right back to the cue tip over the spot you're on the right track. If not I have to examine all the variables involved and identify what I'm doing wrong. I can't imagine any better feedback than that. If you get that working, everything else becomes easier to learn because you've refined your knowledge of stroke, aim, speed and feel. And in my experience, after I had a basic foundation, most misses are caused by a faulty stroke.
Everything you said here excellent and correct.
The straight back drill, or "12-diamond drill" as I call it, is a perfect way for you to test that your tip accuracy, vision, and alignment are all focused on the center vertical axis of the ball.
But that just works for center ball shots. Shots with side spin, and variations of follow and draw, all "feel" different.
I want to take it a step further. I want a player to be able to say out-loud "I am going to use 1:15 o-clock English" (assuming the face of the cue ball is an analog clock, which is easy to understand). The electronic training ball will report back the exact English you used.
If a player is consistently inaccurate applying spin, say for example, every time he tries to hit 1:15 he is hitting something like 1:45 or 2:00, then this could help provide insight into a issue. The issue could be a mechanical flaw, or it could be that his developed feel is a little off and needs adjustment. The issue could be for that particular shot for that particular table layout, or it could be more general.
My point is that "tip accuracy" in particular gets much less attention than "aiming the object ball". I think all players are much better at object ball aiming then they give themselves credit for, and they spend too much time with aiming systems and object ball focus. There is more improvement to be made in tip accuracy and getting your "feel" for all types of shots with spin to match EXACTLY what your brain expects it to.
There currently isn't a product that allows a player to directly measure his tip accuracy for the full collection of shots needed to play real pool, other than training balls with graphics printed on them. The problem with training balls is that you need to manually align them (error prone), touch the ball between every shot (illegal) and then try to find a chalk mark that may or may not have rubbed off (cumbersome). I'm proposing a solution that solves all of these problems; a hands-free training ball.
Of course, you can just do drills like we have been doing for 100 years and develop all of this feedback through cue ball position and time. This product will just give you more feedback to work with and hopefully make your practice sessions, which we all should be doing anyway, a more efficient use of your time. It will also reinforce your game confidence and pre-shot routine if you know you are executing exactly what your brain wants it to for all situations.
I also want everyone to have fun practicing, and actually practice. I've already found that this is very fun to use for both drills and real games.