Oh, I so totally feel everyone's pain.
Usually the ultra-intense volley of super-terrier-terror barking my dogs generate when approached by small children is too horrifying even for most adults to endure. One minute they look like little adorable stuffed animals and everyone wants to hug them, the next, they're all spiky fur, pointy teeth and a noise so irritating that I think we could probably use it in psychological warfare.
So even if an unapproved toddler makes a heedless foray into my 15-foot terrier protection zone, they usually get right back out of it posthaste.
If someone is invited to be close to the dogs, however, they can behave somewhat better. But that has to be under carefully controlled and monitored circumstances, because I don't want to take any chances. They've never bitten anyone (except me, and those were love bites). But they aren't really comfortable around little kids.
I use regular collars and (slowly, oh my golly it took forever) trained my dogs not to pull on their leashes, so they never choke themselves, because they never pull on the leash. For a while when they were puppies, they pulled me everywhere. I tried the body harnesses, and they just got better at pulling (because it's so much easier to pull when you're in a harness - they are, after all, designed for pulling). I believe they work well with some dogs, but mine just thought they were running the Iditarod.