Keep in mind the problem that some people recently had when the Disney VISA
free dining came out.......everyone KNEW that this was going to be a "subject to availability" offer, so calling early meant the best chance of either converting your current reservation to the free dining or making a new reservation for a room that was available.
There are many many many posts from very frustrated guests because they couldn't get ahold of their agent to make these changes for them....and because they booked through an agent Disney can't make any changes or even quote what your current reservation with the new code would be. Some of the guests had agents that weren't in the office yet, weren't calling them back, or didn't even know that there was a code (and the guest had to come to DIS to ask for the various codes to give to the agent) and there were even some who were basically arguing with their agent because the agent "assured" them that the AAA rate or other discount on the room was a better deal for them.....yet they couldn't quote what the free dining cost would be to be able to compare!!!!
My own experience with an agent that works for a company that bills itself as Disney experts was so awful that I will never again consider an agent.
There is NOTHING that an agent can book for you that YOU cannot do yourself through Disney. They have the same codes, the same ability to check if there is a PIN with your name, and if you do your reservation online, it's the same availability that they see....and if you call Disney directly it's the same availability there (the perk agents have is a special phone number so you may get a busy signal and they may get through easier).
Many of these codes have limited availability so when your agent calls the resort of your choice may not be available.....unless you've given them carte blanche to make decisions for you, or a list of acceptable resorts and maximum prices or something....they'll have to contact you and call Disney back again hoping that your choice is still available. Or...you could do the calling, let Disney tell you your options and make your decisions right then, asking questions that the agent may or may not be able to answer without calling Disney back and then calling you again.
I could see where someone living out of the USA should probably use an agent....the long distance calls would be prohibitively expensive, but for probably 90% of the people in the USA they wouldn't be paying long distance rates (most people either have cell phones with long distance included, or land lines with a long distance plan....even those that pay long distance it would be a couple of dollars at most for the 30 to 45 minutes or so that you typically spend on a call making room and dining reservations. )
Oh, and in my case, I was able to get a better rate by almost $200 than what the agent finally (2 days after the rates came out) was quoted.....and we went down line by line and could find nothing different, and she couldn't explain it. Obviously I kept my rate (well, until the new free dining came out and then I had that changed by 7:30 Florida time).