From someone who has a lot of experience here and with Centurion, I haven't seen any of these problems. I never wait on hold. I wouldn't expect any US travel agent to know much about Macao. So when I stay at some place exotic I just spell it out for the agent and tell them to book it and call or email me back with the confirmation. I'm using them for a lot of travel lately and they have been pretty good.
The only problem I have with Centurion travel is getting a receipt for the flights. They can only mail them by post. I'm going to have to work on them about this.