External Access - RD Gateway Manager Really Necessary

Hi,

I have successfully configured the following all on Windows 2008 R2 Servers. Take note I won't be implementing multiple RD Session Host Managers down the track.
RD Session Host Manger
RD Connection Broker
Remote Desktop Web Access

End-users can successfully access the RD Web Access & utilise the RemoteApp Programs internally. I have a very specific domain group specified to only allow the appropriate end-users to initially authenticate to RD Web Access.

Do I technically need RD Gateway to allow end-users to access RD Web Access externally? If no is the answer do I simply on my router just NAT my external
IP address to the RD Desktop Web Access Server & allow HTTPS & HTTP?

Thanks