At our RC/CL club, we have had a couple of kids for the first time try a few CL laps. We have a couple of CL trainers. A Cox 1/2a, and a Testors Freshman 29 w/ OS 25FP. We supply everything in an attempt to get new kids interested in CL (models, fuel, lines, etc. - and also crash repairs). A labor of love, I guess!
We have not had the experience of very young future pilots, but a few in the 10-12 age range.
One thing we noticed. They were able to fly both models in a circle, but the larger model was definitely easier for them. The small 1/2a was less stable and harder to fly, certainly if there was any wind.
The Testors Freshman 29 being a solid balsa wing model that is relatively heavy with a high wing loading can't really do stunts effectively, but will inside loop if the loop is very large. But the larger model was more stable and allowed to pilot to feel the pull of the model. Something that is not experienced with a typical 1/2a model. Basically, the 12-year-olds were able to fly the 25-size model better than the 1/2a.
And on the Freshman, since the newbie pilot will only be going in a circle (no stunts) the model has a very small 1 oz tank that will allow the 25FP to maybe go for 2 minutes. Usually runs out of fuel before the new pilot gets too dizzy.