Different rails Märklin my world .....

My son is really into its child-friendly railway, which he has for some time. Therefore, it made sense to buy another starter for another train and additional rails.
But I've probably read that the starting sets differ in the type of rails. For this, you can not demonize the manufacturer but of course. Ultimately runs this train on its plastic rails as desired and I have just ordered additional set for this. For me personally the rails with metal have liked better, advantages of the plastic system, unfortunately I can not see except a lower risk of injury.
The price / performance ratio, I find still OK and my son plays without my concerns, like so. Can it despite everything recommended for small children.