The 890 is far superior the 780. Just the mere fact that the 780 only has a basic true/false variable ability is reason enough to go with the 890. It used to have an event timer as well, not sure if it still does or not. I'd say the price to go from the 780 to 890 is worth it and the jump from 890 to 990 is more about preference and desire on graphical customization and ability to play sounds.