I thought I would post this extract from the Accident Report that Viper gave us the link to. It refers to a Mosquito crash in which it was found that the later carburettor modification to overcome the negative G effect was negated by a fault in the carburettor that failed to sustain fuel flow to the carburettor chamber.
"In the event that the combined dynamics of the aircraft and float chamber fuel mass caused the floats to be forced towards their fully depressed conditions, then it is likely that the ensuing restricted fuel flow could cause a loss of engine power,
as the residual fuel in the chamber would last only a few seconds."
This indicates to me that the engine cut would not be instantaneous and I simply don't believe that the aircraft would have been accepted if persistent cutouts or misfires were experienced in normal flight. It is certainly not mentioned once in the many bios I have read including those that talk about the nose-over dive cut-out problem.
Is it 0.5G, 0G, -ve G? 1 second, 2, 3? I don't know but it's not 0.25G and 0 seconds.
It needs some research but if there isn't any I'd be happy with -1G and 2 seconds to onset (rpm reduction) and a couple more to engine cut. After all, we're only interested in making normal flight and descent not give problems. When we nose over in combat we NOSE OVER because we wan't to catch to so-and-so - we ain't setting up a descent - and we can expect the engine to cut out. No point in splitting hairs over half a G and a second or two. And that should be acceptable to the Blues because they still get to cut and run. Sorry, make evasive maneouvres
Also I've never read of it being stated as a problem during those RL fast descents and landings made to reduce the risk of being vulched by prowling 109s.