My understanding is that CCTV is very selective when it comes to pick a star to shoot for their series. Basically as the mainlanders are saying once you are a CCTV actor, you are in the front line.
I believe Wallace made a right choice when he left Taiwan for China in 2004. If he stayed in Taiwan, he might just ended up shooting "idol series" like other actors in TW. But it was a disaster for him when he first came to China. he had to start over again as a new comer, particularly when he was already well known in TW.
He gave it all up to pursue his long term career goal as a real actor. He did it!