Flips, not slashes. When you flip you also become vulnerable.
People can run away from you either way, only difference is that now you have to chase them down by flipping them instead of slashing them, you think they run just because they're low on health? Enjoy dealing with trolls (oh sorry I forgot that you're one). This doesn't necessarily make anything faster. That depends completely on their playstyle.
I already mentioned the juggling. The easier solution would be to equip a training sword rather than making a whole new mode about it that splits the entire community, which is a very small community to begin with.