The AT is a "Traction Rated" tire which means the "feds" or whoever rates these things have tested it. Traction Rated means in states where "traction Tires" or Chains are sometimes required in snow you can run the AT and not bother with chans..If you had the MT on and the police wanted to get technical with you..they could make you chain up the MT where you'd just drive by with the AT.
The AT Is "siped" from the factory..there by the "Traction Tire" rateing...I have MTs on my 60...in heavy rain (like you guys in Austin get) I'd way rather have the AT. MY MT's will slide around in in light rain. I'm switching to the ATs on my next change out. I have to drive 200+ miles to get to the desert areas I run in, then there is no mud. I'm tired of the road noise and slow speed "bumping" from the lugs on the MTs..but that is my choie for my situation,,both or great tires ..
If your gonna hit the trails down there over 50% of the time then MT hands down. If this is a daily driver with occasional trail runs...looks like the AT would still be your tire..
Read up on the "traction rated" deal..that should help you decide.