I am on an acass contract based from Mumbai, so far so good, the salary and per diem show up on time as stated in the contract, they have gotten biz class tickets to and from, and they will do what ever they can to help you out concerneing contract travel and allow you to work the rotation out with the other crew members. We are on a 6 week on 6 week off rotation, I extended a bit but was given a financial incentive by the Indian company, which was suggested to me by my acass manager. I have so far been treated fairly , but your initial negotiations with acass must be firm and to your approval, because that is what you will live with.
As I speak, they are a stand up company, and you can fall back on them if the Indian operator trys to push you in a direction you know you do not want or will not go.
Cheers
X man