We have a slant load two horse trailer. The Avalanche does a great job. Most of the time you can't even tell it's back there.
Only complaint I have is the springs on the Avalanche could be a little stronger. The cargo limit on the 1500 isn't really all that high.
So the springs are a little mushy. I have a set of air bags that need to go in for additional support when towing, otherwise the jack on the trailer tends to drag the ground as we come out of our driveway.