RE: new Arf Boomerang 14lb thrust
I built a BB with a P60 for my 15 year old last Spring. The primary intent was to familiarize him with turbines and get him his waiver. Since it flies like a trainer it was no surprise that he passed his waiver test flight at the end of the first day flying the BB. Since it flies like a trainer it was also no surprise that by day 2 he was bored with it. He immediately wanted something more challenging (e.g. faster), in fact he stopped flying it for awhile due to boredom. I have just finished a Bobcat for him with a P80 to get him something faster and more acrobatic. Had we bought a P70 or P80 I would not have had to buy a second turbine just after buying a P60.
I would also strongly advocate for using Jet-1a gear - they are so forgiving that they will make up for the inevitable "11 year old" landing and give him some more airspeed.
Phil