Today I tested to see if we could fit our stoller and the car seat safely into the bakfiets. We can. The carseat base will be strapped to the bike with a seatbelt, just like it would be in a car. The stroller will be strapped to the bike so it can't tip over towards the baby.
Also, the front tire pressure will be reduced some to provide extra cushion on the ride.
This transportation solution has already been successful in Amsterdam
recently in Portland, Oregon.
The solution is covered more here in How Bakfiets and Babies Mix.
Our own government Center for Disease Control reports that motor vehicle injuries are the leading cause of death among children in the U.S. (2006). The leading cause of non-traffic fatalities for kids is the back over...often parents backing over their own children in their driveways, as documented in this CNN video and the Kids and Cars website.
While family bikes are new here, all signs I've find point to them as a safe choice. It's only unfortunate that unlike in places like Copenhagen we don't have five models to choose from.