First, let me elaborate on three possible connection types:
1. Direct connection by an IP address or DNS name. In this case no intermediary server is used. Viewer connects directly to Host.
2. Indirect connection by ID: hosted by us. This is the simplest setup - just follow this tutorial to get everything up and running in seconds. You don't have to change any ports.
3. Indirect connection by ID: hosted by you (GMS). You point both Host (Settings -> Internet ID connection settings) and Viewer (selected connection -> Properties -> General tab -> "Change" button) at your GMS. Note that for Host this setting is global whereas for Viewer it's on a per-remote-connection basis, that is you can have records in your address book that use different types of connection. Once you specified your GMS instead of the default ID server at both ends, use the ID of the remote computer in order to connect just like you would do if you used the second type above.
I would recommend you exactly follow the GMS manual as it explains everything you need to know for this advanced (yet powerful) option.
Don't hesitate to write here if you didn't have any success with configuration.
I've got to say, so far I'm really liking Remote Utilities (and I've used gotomypc and logmein for years). Still figuring out a few things, but that's normal.
Thanks for using Remote Utilities! Don't hesitate to share with us your suggestions right here on the forum. Though we have certain priorities and implement new features in the order of most impact/importance, we always include user suggestions to our wish list and further to the roadmap if they fit our product's general paradigm well.
I'd like to add to what Anton has said. Namely, we are planning to add a simpler version of the chat right into the Full control / View window. The old Chat mode will still be there in case you need more chat features. It's only that the simple chat window/pane (at the right hand side of the screen) will allow you to quickly exchange messages with the remote user during remote support without switching to a separate chat window.