When the Level 81 Nikes first came out I purchased half a dozen of them, I was using the level 71 "X" ball for months. Immediately after playing a practice round with the 71's I switched to an 81 and it was like OMG, I can't miss the ding", it was on the verge of being TOO slow, I'd click too soon at first anticipating it to charge up to the line, then I learned to just wait for it to arrive, it felt like it stayed at the line for a tenth of a second.
Weeks later the meter has slowed to almost exactly the 71 balls meter, today I just practiced back and forth between balls and the differance is so minute I have to actually look at the ball to see which one I'm using. The music BPM theory doesn't make sense here because I'm switching balls within seconds, not days.
I wrote an E-Mail to support about this and received no reply yet. If you watch real close on a practice swing it starts out very slow, at about 1 and a quarter inches it shifts to a higher gear, an inch and a quarter later into another higher gear (I know about shifting gears as I drive race cars), every single time, on every differant browser and computer I use. The first time I used it, the 81 ball, that very initial slow speed that you see continued on all the way to the hit line, it definately has been changed.