I use a 4-12x AO Vortex Crossfire on my CZ455 that I moved over from a 10/22. It works fine, but I don't think the AO is really needed.
Adjustable objective or parallax adjustment need depends on whether you intend to shoot smaller size targets at close range with high magnification. I find that useful for .22lr, but not for the .22WMR.
