I would like to make the main decision criteria the ease of flying and handling. Which of the above flies best? Which is the easiest to land? We have a 300m (900ft) asphalt runway, but I still would like to be able to fly from a 500 ft (150m) runway safely.
Alo seu Herman.. my vote too is for the 339 as I haven´t flown yet the Viper. It´s a super sweet flying airplane, pretty much like a powered glider and very easy to land.
It is worth to mention that it has completely different flight characteristics than the Eurosport, so you may need to fly it first in the longer runway until mastering landings with flaps, without floating it too much.
Enrique