I experimented with Tunngle a bit. Here's what I found.
While Tunngle has networks for a lot of games, 230 just for strategy alone, you can only use one at a time. For example, you can't be logged into HWLG waiting for someone to show up to play while at the same time chatting with an old friend in NTW, or looking for opponents in both games at the same time.
All games use different ports, but the port you set in Tunngle is global, and requires a restart of Tunngle to change it. This is another thing that locks you into one game at a time.
Tunngle is low featured for a chat client. For example, while you can change the "skin" to get a different look, you cannot change the font size or style, which may be important if it's too small for you to read. Other than a sound cue, there's no indication that someone has joined or left the chat. There are no special markers for people currently playing a game and unavailable for chat.
Tunngle is still in beta, so new features will be added. But once the beta period is complete, you'll lose any features that are reserved for premium accounts that require a fee to use every month. This probably won't matter to most people.
All of the above is based on my limited time exploring Tunngle and reading their web site. If I'm mistaken about anything I wrote, please let me know. There may be way of getting around some problems, for example if you can define your own skin you might be able to define the font size as well.
Please understand that not everyone is able to use voice chat, or is willing to. If a lot of people in a lobby are using voice chat, you're locking out lot of people, and I'll bet the percentage is much larger than you think. One reason for the lower quality graphics in the game is to make it more accessible to more people. This philosophy needs to extend to lobby services as well.
Hook