The RED A-03 diesel is liquid cooled, so have very low vulnerability to shock cooling. Cabin noise... I can't say it's more quiet than the piston or turbine, though I do not have numbers. Yes, the FADEC had two "lanes", shutting them both off, removes fuel. On of the unusual beneficial characteristics of this engine, is that as a V12, it can be run on only one side (six inline) should their be a failure on the other side of the engine, everything other than the crankshaft and gearbox are left/right redundant.
As for service ceiling, haven't found it yet. I tried though, at 6000 pounds (900 pounds heavier than a radial Beaver), here's where I've been so far (note the VSI):
