I am a TA, and I go to Disney frequently using the TA rates. I'm not sure if you'd be able to get them by calling any CM or not, I usually use the TA line for all my calls to Disney anyway. The rates are usually around 50% off rack rate. In the past month we stayed at the WL for $99.00 per night before tax, and we're staying at the GF in a few weeks for $189.00 including tax standard view.
The one downside to booking the TA rate is that they aren't always released at the same time that AP rates or other discounts are. I'm usually able to get them a month or two in advance. And they are not room only rates, they are basic plan rates. The only way to book is under the package terms, so you have the $200.00 deposit and then the balance due at 45 days.