I have to agree with the comments made by Pax. A violent encounter is an incredibly dynamic and fluid situation. Any GOOD training is an advantage is such a situation. It puts tools at the disposal of the defender.
My personal opinion is that training should emphasize de-escalation, if possible, and explosive, violent, and damaging tactics if the situation progresses beyond salvage. I think it is foolish to think that a defense class lasting a few days, or even martial arts training over the course of years, truly prepares you for a violent encounter, but I also think that the more options you have at your disposal, the better the odds are that you will prevail. Ideal training would be as violent as real life encounters, but this carries it's own risks to safety. We can only do the best with what options we have. More options are better, as a general rule.