I have never used a TA for any bookings to Disney. I usually stay off site, so using a TA like CAA wouldn't really work, since most of their promotions you must stay onsite to get the bonus.
I have found that by booking everything by myself, I have saved lots of money, but again, I stay off site. If I stayed onsite, maybe it would be worth it. I just find that I generally know more than the travel agents I have dealt with (it's not that I know everything, it's just the TA's I generally have ever tried to deal with knew nothing about what I was talking about). In the end, I guess I just trust the people on this board as well as my own personal experience travelling down to WDW when booking a trip.
Jo