The E911 service providers are required by FCC regulation to ask you for your street address during signup, and then, when you call 911, your address is sent to the emergency dispatch center. If your community supports Smart 911, then yes, it will work with whichever E911 service you decide to use. If you want to take advantage of Smart 911, then don't use your dispatch's local number; calls must go through the 911 infrastructure.
I have no experience with, and frankly wouldn't trust, GV911. It's some random guy on the internet, reselling the service somehow, until one day, he mysteriously disappears. For a bit more money per month, you can sign up with an established, known VoIP provider, like Anveo, Callcentric,
voip.ms, etc.