Just to clarify the sand bags we used were about 16lbs each, we used 2 in this video
http://teamredacted.org/2015/01/05/final-build-update/ and 1 of those is near the center of the robot instead of in the very rear.
Look for the video of our final configuration soon where we show the final balast choice.
Note we never attempted to do a 6 tote + 1 recycle container stack. The most we attempted to drive with was 3 tote + 1 container.