As long as you stick with the antisyphon valves, life is simple, from the viewpoint of ownership. You do have to relocate valves so that they are higher in elevation than the sprinklers that they feed, but for the hundreds of dollars you will be spending up front for to install an RPZ backflow preventer, and maybe even more, in annual inspection fees, the old ASV might not look too ugly.
You would do better to not choose the Orbit valves. Irritrol, a brand owned by Toro for some already-established product lines they acquired, has the
2711APR valve in the 3/4-inch size, and the 2713APR in the 1-inch size. If you were pinching pennies to get to being a user of Orbit valves, you might explore a big box store, to see if you can find these valves in their consumer version (usually branded Lawn Genie 54000) for a good deal less. Pros don't install the consumer version, because it lacks the manual-operation lever found by the solenoid, although the bleed screw still allows for manual operation.