TRA and Rada Lyric here.
We just brought our kids skis they liked the look of as I figured it was more important to like and want to ski than the result.
My son skied the TRA from around six/seven to twelve years of age. He was skiing 18m at 49km and 52km when he finished on the TRA. Probably should have moved him off it a year or two earlier in hindsight.
The more difficult decision is what to get when they get to the end of the TRA capacity Radar, D3, Connelly, what level and length new, second hand.