Here's a funny stat for you -
I have 45 ditches overall in tanks, all which come from being flipped over from a hill or tree.
If you break that down vs 200 deaths in a tank there's a good chance 1 in 4 sorties I will flip over (Hooter would probably say its a hell of alot higher)
The reason I flip over is mainly the graphics are set so low, hills are nearly impossible to judge distance wise or elevation so I normally always ram them at full speed and on a bad angle, only if its in front of me and I am doing 5mph will I survive not flipping.