The classic traditional vs MMA argument... I don't think I have ever seen a thread on this that hasn't turned hostile. My opinion... I think there are too many variables. I think it depends on the person, where they train, there size and level of physical conditioning, and most importantly their mindset. I've met dangerous mf's on both sides of the fence and an equal amount of shitbirds too.
I usually tell people who ask me how to get good fast to start with boxing/muay thai, then something that teaches throws because I feel that combo gets people decent fast enough, not to mention gets them used to the contact and adrenaline. And as far as the dirty stuff goes, honestly, who needs to go to a school to learn how to grab balls and gouge eyes. It's a time/benefit thing.
But I also have a tremendous amount of respect for many traditional martial artists. They learn many many effective techniques and have alot of effective conditioning drills. Weapon training also.
My advice to you is to do some research. Decide what you want and how much time you have to dedicate. Check out all the local schools and gyms. You might find what you're looking for. As far as mantis goes, when I was a teenager I was big into Shaolin Kung Fu - I learned a couple of Mantis Forms - they had some cool techniques but nothing a thought was the ultimate truth in hand to hand combat. I would trade that time for something else in retrospect. Good luck.