Suppose it depends how much fuel you have onboard and how much damage you do in the process of ditching. Full tanks, with no leaks might lead to the aircraft partially submerging, but remaining afloat as fuel is lighter than water. Never done it so I can't really speak from experience.
Could always get an "air pocket" to go between the chambers of your life jacket if you're worried about not getting out. A small pouch which attaches to the life jacket, and in an energency, you rip the velcro, and pull out a mouthpiece and nose clip. Before you go under, you pull out the mouthpiece and inflate the bag (which also has a small air cylinder activated by hydrostatic pressure), and you can get up to five minutes of breathing under water. Used to carry them on North Sea helicopters, and they work really well (though never had to use it in Anger
)
EA