Almost All the way down. I think the game looks smoother when you do it. A lot of the dunks and alley oops looked better after I did this, and the game feels more realistic. I wonder if you can turn up player acceleration in the full version. I recorded some vids of me playin with the slower speed.
Spain Vs France, (I'm Spain) - Starter Level
http://youtube.com/watch?v=dTRI94IJjsk
Spurs Vs Cavs - Superstar Level (I'm San Antonio)
http://youtube.com/watch?v=0_llktEO6xI
Spain Vs France (I'm Spain) - All-Star Level
http://youtube.com/watch?v=moQ9IEUYkjQ
** Yes, I mis-timed that Alley-oop! lol