I have the Pulse 60 with a Saito FG-14 (14 cc) 4-stroke petrol engine. A perfect combination. A DLE 20 would be far and away excessive. There are a few Chinese 15cc 2-stroke gas engines which should be fine.

The Saito gas engines can be fiddly to tune, but have extraordinary economy if you fly a lot and are quiet. I also have the FG-20 with which I have had no problems. The Saitos are very expensive, but can pay for themselves in fuel costs even over a 2-stroke gas engine.

Many people have had problems with the Saito gas engines, but I'm not sure if it is the engines or people's expectations of them.