Cynthia actually starred in a few films with Michelle Yeoh (AKA Michelle Khan) and became a huge star in Asia. She has made over 30 films there. Her awesome trademark -- the scorpion kick is legendary. Sadly, this demonstrates what I've been saying. Hollywood has no clue how to handle women in action roles. They didn't even know what to do with Bruce Lee. Take a gander at "I Am Bruce Lee" where Gina pops in and talks about him and his influence. It makes you very frustrated.
Michelle got her big break with a role in Jackie Chan's Supercop 3. I LOVE that movie even though the voice overs are awful. It sounds like a really bad Japanaime cartoon. Chan thought Michelle upstaged him in the fight scenes so he threw in the big helicopter stunt at the end hoping to even it out. She still makes films in the east and Cynthia, who never starred in anything major from Hollywood, operates her own martial arts schools here in the U.S.
As far as comparing Gina and Cynthia as actresses -- In my opinion -- Heck yeah, Gina is a lot better and a lot more intimidating. There really is no one remotely like her in film.