I know that Zenoah's are heavier than the equivalent displacement ZDZ but the performance is still very good with the GT80. If you are using the GT80 stock (with spring starter and magneto and stock mufflers) then you will be carrying a lot of weight around. I changed mine on a Great Planes 330 to have no starter, Bisson mufflers and CH ignition. The weight change made a HUGE difference. The altitude that you fly at will also make a difference. I noticed this when I was using the older 74cc Zenoah. I had it in a Lanier 33% Extra. At 5500' altitude it was a dog, but at sea level it performed well enough for intermediate IMAC.

For availabilty and cost reasons alone the Zeonah is a very good buy. (I currently have both ZDZ and Zenoah engines - both are EXCELLENT products.)

Have fun and safe flying!