My choice would be the slash for a 4 year old because it is really strong,water proof,and has an excellent warranty on top of that.And if it breaks,then you have rpm hops for like 5 bucks more and they will never break.You really can't go wrong with the slash.The slash is also programable to where you can cut the power in half so he can learn the basics first and than you can bump him up to full speed.If you want to stick with the associated than get the sc10.I bought mine about a month ago and love the thing.It is very durable but i doubt it can handle a 4 year old beating.I would go with the slash overall because it cost less and will be a stronger car for him.
