HitTrax has algorithms for a variety of field dimensions and defenders abilities. If you have an 8U group working with it, you can "down tune" the field dimensions and ability of the fielders. It also tries to mimic field "reputations." For example, if the kids decide to hit in the SF Giants park, a ball hit at 85MPH and a launch angle of 25 degrees to Left Center generally gets caught. In contrast, the same ball hit to Right Center ("Triples Alley") will get down for a triple. There are also some glitchy hits that get down like bleeder-flares to the short outfield, whereas hard hit liners in the same direction seem to mostly get caught by the MIF. And part of the fun is the boys figure this out over time and start exploiting it when playing in Hit Trax "games."
My son's instructor has been shooting some video of his ABs this season and is putting an edit together to help market the PG Indoor League as well as his facility. Hopefully that'll get posted somewhere and I'll be able to link it in this thread! 