Yes, the wall thickness of the hat is a concern. That's why I had to take it a step at a time, the less material taken off the better, but without machining the hat it simply is unsafe as it will wear through the seal. Having written that, I have 2 pair of old swap meet rotors, worn past their limit, bought for the hubs. The hat wall thickness I ended up with was comparable to the thickness of the old worn rotor hats, about .220" to .230" . The newly machined rotors on the car have a hat wall thickness about .230" That's the first I've heard of the Taurus rotor hat failures, I owned an '87 Taurus, and had issues with warping rotors, but no hat failures, fortunately.
