None of our scopes have a variable eye-reliefs when the maginfication is changed although the FOV (field of view) is much larger at lower magnifications.
The problem we found with a variable eye-relife is that you can quickly shoulder your rifle and unknowingly have your eye to close to the scope which can cause a black-eye. We just had a customer who had that happen this past week. With a fixed eye-relief this will not happen because you "wont" be able to see through the scope if your head placement is to far out of range. Keep in mind we are not saying your head placement cannot move in or out slightly, we are just saying there isnt as much variable.
MO