The Harris is a great bipod, I've used it and bipod like it for years. However it does has some things that I don't like that's inherit in its design. The Harris uses Springs to pull the legs back up against a stop, which means there is only a folded or non folded position. This also makes it hard to "load" the bipod, put forward pressure on it, as it tends to slide, especially on hard surfaces which can lead to bipod "hop" if your form isn't perfect. Mine isn't. It also doesn't swivel side to side.
The Atlas has 5 settings the bipod can be in, folded forward and backward, 45* forward or backward, and 90*, also the legs can be in either position regardless of where the others at. There is a but of play in the legs, which allow you to load the bipod forward so when you shoot there's weight to counter the recoil, you can get away with a little less than perfect form. The Atlas also swivels 30*, it isn't much but it's useful if your in a position where the legs can't move.
I'd like to get involved in. "tactical" rifle matches, which depending on the course could have you set up in various positions, and are purposely made so that you have to think outside of the box. I've seen competitors get set up in an area where being able to put one leg of the bipod forward and backward still gets them a solid rest where a Harris wouldn't work. The atlas is just more versatile.
I still love my Harris, it'll go on my 22 target rifle, and the Atlas on my other rifle. They're both great just serve a little different purpose.
