A Mike says: There is a straightforward answer to this one. If there is a chance you will be using add on night-vision equipment on the scope, side parallax is essential. If not, no. While I have heard of some shooters who use scopes without parallax adjustment in conjunction with night vision, unless it’s for really close rimfire rabbit shooting it will without a doubt cause problems. Most of my own scopes have side parallax and they are ideal for whatever fox work I am doing.
Incidentally, steer clear of parallax scopes where adjustment is located on the objective lens. While these work perfectly well, if you are using an add-on and shooting off sticks, it can be a real stretch to adjust your scope. Side parallax adjustment, on the other hand, is perfect for this purpose.
Mike Powell, Professional gamekeeper and foxing expert