Eminence wrote to say that they have finished running magnetic FEA simulations and found that a flux stabilization ring can be added and electro-mechanical parameters be maintained as described in the thread above. But the way this was accomplished in their simulations was to add add steel to the core surrounding the cooling vent and reducing its ID. This was done in order to replace the steel that was removed to add the flux stabilization ring.

I have asked that they consider other methods of increasing flux. Possibly using a larger magnet or use another alloy, perhaps a layer of neodymium. Decreasing vent size is an option, and it may be worth testing to see what the end result would be. It is possible that this is a non-issue, we'll see. But my gut feel is that I would prefer to address this by adding magnet instead of by adding steel and reducing vent size.