So what do you gain? Almost certainly you will still need all types of breakers in your deck, so you do not save slots. Actually this card probably eats up extra slots because you will be tempted to cheat it out. You are including this card solely for its special ability, but I guess we probably knew that going in. Unfortunately, this card is so inefficient that you are better off just breaking the next ice normally. Furthermore, unless you are Kit, you are counting on the corp to position their ice a certain way. Good luck with that. Finally, there is no guarantee that the ice behind the piece you break has less than four subroutines.
Pro tip, use typical icebreakers instead of Mass-Driver