I gave my at-the-time eight-year-old my older Ticwatch. They had no interest in the step tracking or even what time it was -- they used sleep tracking as an excuse to wear the watch to bed and play games on it.

If the Syncup has some sort of parental controls, or if your child has some sort of impulse control, you might not suffer the same fate. BUT the question I'd ask is why a watch, smart or otherwise. Will the kid actually set and listen to alarms, do you want to be able to send them messages, have they benefitted from knowing what time it is? (parenting hard, I am not a professional, do what works for you and yours)