Nope, we never really used our stacking mechanism. We had arms that could move up and down, the little arms attached to those that moved side to side(for picking up totes) Our engineers came up with thise whacked out pulley system that everyone on the team thot was iffy, but ended up being alright. We primarily used our stacker to plow thru the totes in our auto mode, but our main strategy was to get the KOH points at the end of the match. We pretty much depended on our awesome tranny (8 ft/s high speed, 1 1/2 ft/s low) and its awesome power to get us up there and not be moved. Plus, the grippy tank/conveyor belt treads we used were had awesome grippiness on the top of the ramp and we barely ever moved.
If ya wana see any pics ...
http://www.pbase.com/shsrobotics/our_robot