I have been in many a discussion re ditching. (Fly C130)
The only ditchings that have occurred were either
1. Out of fuel; or
2. In a world of hurt before the ditching.
The bottom line is this. If you are over land you will do anything to put down on a strip. Same for over water keep it going as long as possible. Only when the situation is dire would you consider ditching (or crash landing)
I hope none of you out there or myself for that matter end up in that situation because if things are that bad we probably will not survive.
Cheers