RE: TURBINE CHOICE
Apart from the size and weight, the problem with the Jetcat is fuel economy. Whilst I am waiting to put my Merlin 90 in a Viper, it is going to go into a Comp-ARF Flash to replace an old P-80 that is currently fitted. The reduced fuel consumption means that I can do away with the wing tank and still get reasonable flight times.
Although there looks to be quite a bit of room in the Viper the stock main tank isn't huge and flight time appears to be somewhat restricted with the P-80SE. Of all the engines listed the only 2 I can really separate from the rest is the Jetcat and Kingtech. The Rabbit, Merlin 90 and Booster all look awesome. I might have gone with the Booster had I seen them in the flesh but I have witnessed the Merlin 90 running and it is great. I'm sure the Rabbit would be equally as good but it doesn't quite have the thrust of the Merlin and sending it back to the US from Europe for warranty issues would be a pain.