You can usually count on hobby shop people to know more than the average guy about the products they themselves sell. Contrary to some of the threads you'll find on RCU, there really isn't a bad brand on the market today. MDS was a bad one, and the very first run of Evolutions had problems, but I'm not aware of anything currently made that has a bad reputation for reliability. 2 stroke glow engines have been made essentially the same way for a good 40 years now, so any design idea that won't work has already been eliminated. So then you're left with quality of manufacturing, parts support, and warranty. There is most definitely a difference between the $150 .40 size glow engine and the $79 one in all of those areas. But in the hands of a knowledgeable user, they will both power a trainer reliably.