Assumed "dangerous" has nothing to do with my decision to stay out of Open. Killing newbies out of sport, especially if they can't defend themselves, is a pretty reliable strategy. This is exactly why many abusers, whether in-game or not, prefer to use it. However, it's not a "fight" or anything I want to be a part of. If you've ever seen this winning tactic used, you haven't seen a fight, you've seen an assault.
In an assault, the attacker has a sense of success because he initiates the violence and dictates how it plays through. In other words, he feels relatively safe, because by attacking himself and defeating his opponent from the shadow of surprise, he can protect his own well-being and his back quite well. Although the trip is guaranteed to be full of adrenaline and excitement, he doesn't have to worry about his own well-being.
Not so in a fight. A fight is a longer confrontation with someone as tough, if not tougher, than you. And that someone is as determined to beat you as you are to beat him. It means that the only thing stopping him from doing things to you before you do them to him is you and your skills in combat. So here's a quick lithmus test to see if you're in a fight - you let your best attack go and it doesn't affect the target in any way - and then he throws his own attack at you.
In a fight, the confidence that is typical for an assault flies out the window, because now the fear of losing comes into play. And to put it mildly, this usually leads to a rampage from the attacker's behalf, especially if his own defense crumbles under his opponent's attack. Now, he will be in quite a hurry to get his opponent down before taking the fall himself. So as a rule of thumb: If you don't feel the fear of getting hurt, you are not fighting, you're assaulting.
Incidentally, it's also one of those situations where a ganker's "PvP" works exactly as he's practiced it. He is safe because he has the initiative and his victim is in a state in which he is unable to mount an effective resistance, let alone an effective counterattack. For many people, that feeling of being so smart and sharp when it happens to them is because they have imagined themselves to be a virtual killer commando and thrive on it. And it must also be said that assault and abuse comes with a terrible rush of emotions, adrenaline and endorphins. In fact, it is a form of activity that many get hooked on.
This particular human condition has a technical name: Sadism. The problem with sadism and abuse as a hobby would be, of course, when the sadist finally happens to end up in circles where such behavior is not condoned or at least somewhat tolerated, sooner or later he runs into someone who a) receives his best attack and doesn't budge, b) is faster than him to "pull" (making him the victim) or c) he ends up rattling the cages our delightful prison worlds.
So in what comes to anyone's choice between Open, PGs and other Hotel Californias... I'd say it's more of a "birds of a feather, flock together" thing.