Agreed, I have been on iOS 8 since it was released as a beta. Wifi call works great. Don't see the point of the router for iPhone 5s and beyond...
I'm not clear on why I would need additional hardware to enable WiFi calling. My 5s does very well on WiFi calling on iOS 8 with nothing besides my normal router. Is this simply for QoS purposes? If so, most any router can do that.