I personally NEVER recommend ANYTHING done behind the neck. Sorry, but statistically, working behind the head causes more injuries, so I don't see why anyone should risk it. This has been debated many times over, and there will always be advocates of doing it, but usually just because they haven't had injuries themselves. Unless you're a wrestler, there's virtually nothing in life that requires a press or pull behind your head. And therefore, the shoulders aren't designed for it.
For rear delts, I'd be more inclined to recommend ROWS (yes I said that), reverse d/b flyes, 1/2 rotation laterals or just letting them develop naturally with your compound movements. (like overhead presses)
Incidentally, proper d/b laterals would be done bent slightly forward, arms swinging 30 degrees to the front, stopping at level. This will hit the mid and rear delts nicely, and not impinge the rotator cuffs.
For rear delts, I'd be more inclined to recommend ROWS (yes I said that), reverse d/b flyes, 1/2 rotation laterals or just letting them develop naturally with your compound movements. (like overhead presses)
Incidentally, proper d/b laterals would be done bent slightly forward, arms swinging 30 degrees to the front, stopping at level. This will hit the mid and rear delts nicely, and not impinge the rotator cuffs.