Quicksilver is great. They are always quick to respond to e-mails and Gregory himself called me recently to verify our arrangements. They are worth the few extra bucks.
I have a friend who just returned from Disney and she told me it took 6 hours from the time the plane landed to get her luggage at the resort. Yikes! I hope that isn't the norm.
I talked to Disney and they told me that guests do not need to have their TA's call to make the dining reservations. They said they could search by reservation number, which is actually faster than searching by the agency number, and as long as I wasn't trying to modify the reservation I could...
If you book with a TA, why do they have to call in? As long as you have your reservation number from them, can't you do it yourself? They may not know your touring schedule to make any time adjustments if what you want isn't available.