It's cheap insurance. It protects the torque converter and...everything...in the transmission. Definitely recommend it.

There are a lot of different opinions on oil brands , some people say pretty much all synthetic is the same; personally, I've seen some tests with Amsoil's Signature Series ATF that won me over. They claim twice the resistance to heat breakdown vs other leading synthetics, "reserve protection" vs heat. And have ASTM testing to back it up. Basically you can run severe service at regular intervals. Third party testing and my own experience seem to line up, it's very very good fluid.

Regardless of fluid you use, make sure it's the right spec for your vehicle make, and change it at the appropriate interval, and you'll enjoy a VERY long transmission life (unless there are design flaws, like Dodge Grand Caravan for a few years, or the Ford Focus with the disaster of an automatic clutch).