Shawn: I just put together a cheat sheet here. I hope it is helpful!
Tom: :) Yes, hypothetically it would be quite difficult to remove the slot covers without a Dremel. The material is polycarbonate – it is sometimes sold under the more familiar trade name Lexan. In thicker sheets it’s used for bullet resistant glass.
Regarding legacy trap: You hit a nail right on the head. The safety standards are written for a previous era. One of the tests that really set us back was a test designed to check if the paper in your transformers was absorbing water.
That said, I do sometimes use my Mooshimeter in my pocket with the leads hanging out. I find that to be quite convenient. And one of the use cases I want to enable is the meter in pocket and text-to-speech in the app telling readings to your headphones, so both your hands and your eyes are totally free to handle the leads. So I think the full CATIII 600V rating is important.