I've been using the Atlas bipod with the ADM mount for about two months, and I'm glad I went with it.
The thing that surprises most people is how light these really are. They are well-built and beefy-looking, but an Atlas with the ADM mount weighs *less* than a stock Harris BRS, and that's even without adding a QD pan mount to the Harris.
These do take a little longer to deploy than a Harris because the legs aren't spring loaded. This can be an issue in something like a 3-gun match where a few seconds are significant, but it really isn't even a consideration for most types of shooting.
On the plus side, the lack of external spring makes these quieter to deploy and easier to use for bracing on a barricade or blind window. It also means that you don't have to worry about your bipod folding up on you at an inopportune moment.
Though the Harris bipods are time tested, the Atlas has shown itself to be worth the premium for the kind of shooting I like to do.