My young lad is now in an Adult XS size. In the local MTB program he has been riding an X-Small Norco Storm 27.5 and it fits him well. An X-Small Rocky Mountain Growler is available used locally for a decent price. Would this be too beefy/heavy a bike for a 10-year old? I feel the plus tires would give him more confidence on rough terrain but the extra weight/rolling resistance would make him have to work harder which wouldn't be ideal for encouraging him. Anybody have any thoughts on the Growler for a kid?