I'd like to chime in, having seen some rule modifications at BattleCry this weekend.
BC had a large box in the middle zone around each tower, in which robots were allowed to expand to finale volume. I think this eliminated a few unnecessary penalties, but didn't have any major effects. As
XaulZan11 jokingly alluded, no one (I hope!) is going to rebuild their robot to violate the spirit of the rule just because the letter has changed.
Incursion penalties for driving over balls were rarely called at BC, although this was due to the referee's choice, not a specifically announced rule modification. In general I felt that this was a good thing, since accidentally driving over balls was common.
I would suggest that penalties not be called for robots which exceed the allowable volume because a chain falls off or other part of the robot breaks and drags around outside the frame perimeter. In my opinion, the penalty just adds insult to injury and doesn't improve game play.