I agree with you. I looked at the rating of the ring AFTER the mill was in the workshop and it's only rated at 0.63T. The machine weighs about 1000kg so I won't be gambling with the ring again. The intension was actually to lift with the sling as that's how they show to do it in the manuals, but it ended up getting lifted with the chain.That lifting point where the ring is, is NOT designed to lift the entire machine.
This doesnt mean you can't get "lucky" once in a while BUT using that lifting point for the entire machine is like rolling dice in Vegas....