How does a low wing help someone who is nervous with a LT-40 shoulder wing trainer? He needs something slow and easy and cheap to fly. A second hand plane is good. I suppose when some people have been flying for a long time, they forgot what it was like to start out. I teach my kids to fly, so I taught them on a Butterfly with a .20 on it, just a simple three channel plane that gives you several seconds to correct. I wouldn't put anyone in a low wing trainer who is having trouble with a LT-40.
The references above explain why.