I've thought about this flying over Idaho backcountry. If ya have to go in, land upstream.. Trees are usually bad, so, creek bottom is the best choice in a lot of cases.
If ya land upstream, when or if, You flip over, that puts tail upstream. Windshield will probably be broken out, and instead of being a water scoop, fuselage upstream will give ya a little more time to get out. Also open the door prior to touchdown.. When your upside down, I know.. it's disorienting. Hard to find door latch, etc. And after you unhook seatbelt, your sitting on your shoulders, very uncomfortable, disorienting and even possibly with your head in the water. So prethought and open door might really help.
Upstream landing should also gives you slower forward speed if you flip, from the water speed.
Strong current could take plane away downstream, ya might have just what your wearing.
Hope none of us never have to do this, but I think it could really improve survival odds to land upstream.