I've been considering CENT and this discussion has been really helpful so thanks for all of the comments. Nothing I've read says that now is the time to pull the trigger.
One thing I wonder: are the problems with the travel service just symptomatic of larger problems with Amex travel? I worked for a company a few years back that used Amex as the exclusive travel agent. They were terrible in every sense of the word. Terrible service, terrible attitude and a truly shocking number of mistakes in bookings.
Have they improved? I'll put it this way -- for years I've done most of my family trips for free using Amex points by booking through Amex travel. Now, (and I know how this sounds) part of me is actually glad we are out of points so that I can book through Orbitz or directly and avoid the hassles, errors, and the comically bad website.
Perhaps the CENT personal travel reps are the best they have and that is just not very good?