I'm no expert, but here are my initial thougths on the accident.
First, note from the picture below that the airport is smack against the water. Given that the airplane went down in water a few minutes after take-off, it seems reasonable to assume that it took off on rwy 34 (I did a search for almanac data for Anacortes, the closest weather station, to look for wind direction that day, but without success).
Second, info provided by the surviving passenger suggests that indeed both engines quit, after a short period of running rough and after the pilot seemed to be switching tanks.
Third, the combination of rough-running (and perhaps underpowered) engines shortly after departure and the pilot's attention to switching tanks and re-starting the engines may explain why the airplane didn't glide and instead "dropped like a rock..[and]...hit real hard and all the windows blew out".
Fourth, it is interesting to note -- heck, not interesting, but almost incredible -- that despite this being described as essentially a "crash" (as opposed to a controlled ditching, with soft touch-down on the water), "both occupants successfully exited the airplane before it sank". Although there isn't a wide body of data on how long a Skymaster will remain floating before sinking, data from other aircraft suggests that it might float for several minutes, and this accident supports that.
Finally, it is unfortunate that the NTSB report does not state why the pilot died after exiting the aircraft, while the passenger suffered minor injuries. Was it a result of major injuries suffered at impact, did he drown (and was a life jacket available), was it exposure in the cold water? Also, it would be nice to know if the gear train was down (touch-down in water is safer with the train retracted) and if the passenger saw in the pre-flight if the pilot extracted fuel from all tanks and fuel strainers until there was no water.
On the basis of what the NTSB report has, my take is that any double engine failure after take-off -- whether over land or water -- is likely to be fatal. In this instance, with the impact described, I think I would rather have been over water. In my "Ditching" page on
www.SkymasterUS.com I cover the preparations for over-water flight; having the aircraft in perfect condition and carrying life jackets are key recommendations. And maintaining control -- "flying the aircraft" -- is of course crucial, regardless of whether you're over land or water. And this accident doesn't change (and perhaps supports) the statistics, which show that controlled ditching is as survivable as an emergency ground landing away from an airport.
Ernie