I've only got one of the cardboard KR cases, and that was because I changed my WH army about a bit so needed more infantry compartments. Going to the club and to events I use the KR double aluminium, which looks dead swanky in its black shinyness. My regular WM & WMA opponent uses a single aluminium, as well WM and WMA armies don't take up anywhere near as much space as even a small WH or 40K army now do they?
Anyway, I've dropped my KR case a few times on it's side and so on. So far no damage to any of the models inside, despite there being a mix of pewter, lead and plastic in my WH army. I imagine that your average WM or WMA army would be very well protected indeed. You can get extra deep trays that are perfect for cavalry for example, just figure out the depth of your tallest banner, etc... and there you go, that's what you need...