I knew they were metal casing, that's not really my question or issue.
RJ designed this based on Northern Tool . The Northern Tool might have a larger size, thicker metal, better heat dissipation, etc. I don't know and I bet no one one here does AND more importantly knows how each one of those factors might affect the Aether. So the best way to test the change in design (new HD case) is to test it.
Testing it involves putting it in a HD case, and seeing if there are problems.
So the question remains, has anyone used the metal HD casing and had problems with the Aether failing because of a change in design.