Bringbackthe80s,
The contracts are 3 years in length at this point. It is possible to be offered a permanent contract within the 3 years, but generally this would be at the end of the first contract. But what does a permanent contract really mean? Not much in my opinion, the conditions for termination or resigning would be the same except that you would not have to worry about renewing the contract every 3 years. Note of course that to gain permanent residency in Hong Kong requires that you have lived in HK for 7 years: is it worth? I am not so sure. But it is a goal for some.
But HKA doesn't hold much water in my mind, an instructor that I knew there from the Philippines was released following an incidence in which he was stuck in the Philippines due to a Typhoon last year. He took the initiative to call the company to tell them that he would be unable to make it to work on time and could they make the flight another day or give him a later flight. Well, he thought that his years of service there on a permanent contract gave him some more latitude than anyone else since he had provided many favors to the company in the past. So, the company ask him to come in as soon as he could no problem everything would be ok or so he thought. Skipping to the end, he was offered a 1 year probationary type contract and I believe reduction in pay for 2 or 3 months. He balked at the idea and they promptly released him. Now, to be an instructor, you have to be pretty squeaky clean, so I don't think there were other additional incidence that added to his termination.
You are always one breathe seemly from running a foul some aspect of the system at HKA that can get you released. So, when you go, keep your head down and stay off the radar. The company is not your friend and they will prove it to you when you run a foul the system.
So, I wouldn't worry about a permanent verses renewable contract. There's hardly a difference.