EDIT:
A few stats will post...the ones I know of are tournaments entered, points earned for the strokes you took before you bailed (a good thing) and anything that happens to balls (lost or wearing out) will not cancel if you leave. I've also noticed that closest shots in a CTTH completions do not cancel if you leave the game. Leaving a round early sacrifices the round completed bonus points as well...including practice rounds. Since September, except early after promotion to the next tier, scoring averages are not suppose to go up after a bad round...so the only real advantages of leaving a round early might be to save expensive balls for later and to save time.
Joey