"It's not a good car, it's an amazing one. Most people I know prefer it to the full version because they find te extra servo unnecessary and overly complicated for a crawler"
"I have the sport (my wife's) , defender (mine) , and tactical (my son's). The sport is an amazing truck. Your son will love it. It's very capable when crawling, but does great on the trails with better battery life vs the other two.
If he just wants a nice truck to take out of the box and drive, the sport is an excellent choice. If he wants to customize everything, the Defender is my preference. But the sport has less parts to worry about and it's likely going to be better for someone on a budget.
If I were to get another truck it would be another sport."
Just a list of links about the TRX-4.