I closed down the "Unofficial OcUK TS" to start using Discord.
For a start it is free, the UI is better, cleaner, easier to assign permissions, you can post links and get to preview what it is, think facebook timeline feed but with an in-built talk function similar to TS.
You can either download the app, or you can run Discord via the browser. If works via Andriod and iOS also.
You can have as many talk and text chat only channels as you want, you can have as many servers as you want.
I have had a few issues with it but tweeted the dev team and got a response within 5mins each time.
The usage on cpu is very low and it can be minimised to run in the background if you are not interested in having the UI open. You can mute other players from talking, you can also set a different volume for each user. All very easy and quick to do. The voice recognition comes through clearly and imo better than TS. Sometimes you can suffer random dropouts but they last seconds before you get reconnected. We have had around 15-20 people using it at one stage and it doesn't seem to suffer any negative side effects.
For me it's night and day better than TS.
I've not really come across any distinct disadvantages apart from it having no soundboard option, but I believe that will come soon although maybe in a paid for feature per user.