I thought it would be like this, but it doesn't really seem to be the case. I posted in the patch thread about the 0 slider green release bricks, but unfortunately when I bumped the slider up even one point the A+'s and swishes started coming. So there's some pretty weird behavior with the meter and the sliders going on, and just playing with the shooting sliders really low is going to result in only green shots going in, and everything else missing.
If you're a meter god it's ultimately going to be like the other guy was saying - becomes a game of whether or not you can hit a perfect release, rather than ratings.