I dropped my mega a few times with no problem ,once I accidentally caught my headphone cord with my hand then it went flying to the ground like a sling shot and survived. A few days ago though, I dropped it face down on bitumen and the screen cracked from the top corner going down towards the middle. It was still functional straight after, but about half an hour later I couldn't swipe to unlock it. It was a rainy day so I'm thinking maybe water seeped in and stopped it working? Either way I think it's a write off
The cover I had covered the corners and sides, but had openings for the front top and bottom portions. I think if I had a cover that covered all sides completely it may of survived.
I think it all comes down to luck and how the phone lands, if you have a cover and it hits a corner that is protected it should survive.