Getting your kids off their trusty softboard and onto a "fibo" is a big leap for most (parents and kids). The questions are; do you go for a new shortboard or beginner board? Or, do you get them on a crappy hand me down so that it wont matter if they trash it in the a) shorey b) car park c) stand up paddle board crushes them etc etc.
The answer is, it depends on the kid. An agile, quick learner is bound to go well on a shortboard but they wont catch as many waves. If you can help them position in the line up it wont be as big an issue. If they are out there along mostly without pushes or line up help then a bit bigger board will help them in this transition faze.
Talk to Mark for the inside info to get on the right board. We may even have some 2nd hand grommet boards that kids have grown out of.