It could well be that Vonage and the others actually do route to
areal honest-to-goshness 911 service now, but they didn't in the
past. They routed to some other place. And there are still
limitations, of course.

I definitely think that the VOIP is a good option, but you really
should have a second option, either a landline or a mobile, for
emergencies or outages, because both can happen and you don't want to
be caught unawares.