Hi,
I would second what JNorton said........... the GP ShoeString Racer will slow down but its completely different to land....... i think your son needs alot more expereince yet to fly that...... i would say its more a 5th - 6th plane............. it can snap and u have to know how to get out of it quick.........
My ShoeString Racer has a 91 Saito Upfront and even one of the most experienced flyers at my field doesnt like to give it a go as it scares the hell out of him

MY kinda plane
Soo maybe by all means build it but let someone else fly it first and maybe put ur son on a buddy box until he gets used to it..... thier no shame is being attached by a cord still after youve soloed...... rather that than destroy a great plane
Good Luck