Any 3-9x40 will work on them and look just fine, realistically there is so little noticable difference between 2x and 3x on the bottom end that it is not worth worrying about. There are some 2-7x scopes out there but I can't think of any that have AO or Side Focus.
As far as the AO - if you are using it for a hunting scope then it absolutely is not necessary, if you are using it for target shooting then it is good to have to reduce parallax. Consider this - have often in a hunting situation do you have the time to fiddle around setting the AO to the "guessed" at yardage.
A perfect example of this is a good friend of mine that I have seen miss numerous coyotes because he is busy adjusting his AO or magnification setting and the coyote is usually gone by the time he gets ready to shoot.
drover
