Pilots -- General Aviation: For a long flight over water would you prefer a twin piston or single engine turboprop?

I read about the Celera when it was posted to the GA omnibus thread:

I see hoax (or at least ridiculous levels of wishful thinking) written all over that thing. I’m now old enough that I could be proven wrong as a lot of geezers eventually are. But the progress they’re talking about having in the bag is far and away beyond what much better-funded R&D operations have failed at and are failing at.