Here is my opinion,

GET a small 50 to start with. Get one that has a remote kill switch. I know the Dinli DIno does. Not sure about the Raptor. WHo cares that the machine will be too small in a year. That is a LONG time to a 5 year old. Plus, The little machines with all the safety stuff can be sold almost instantly once you decide too. What is the most you can lose. $300- $400? What can you lose if your kid gets in trouble on a bigger bike????? THink about that a long time. Also, On the throttle limiters. The only thing the throttle limiters do is limit the power, not the speed. They can and will run damn fast if they get going down hill. My guess is 99 out of a 100 wrecks happen going down hill anyway. Have you ever wrecked a car going uphill?

Be smart and bring your kid up in stages. Make them tell you they want to go faster. Make them alway wear there safety gear. I do not let Koty crank up his machine unless it is on. These machines are inheritly dangerous, let's reduce that risk instead of adding to it

 

Great response TRex! I agree...we do have throttle control on our pred 90, but it also had a kill switch.
They must wear their protective gear, and the two younger(5&6) can not go off alone...not even a few feet away. An adult has to be on a quad at all times following. We test them by riding on the back of the pred 90 with them and on command they must break..go...break. Gives you a good idea of their mind/reflex actions.
It is all in the training!