TaigaChat Pro brings to the table a wide array of commonly-requested features, along with many improvements of my own concoction to make TaigaChat Pro more than an old-fashioned shoutbox - it is now also suited to replace highly-concurrent Flash, IRC and proprietary chatrooms.
For your money, you will not only receive a significantly more versatile and powerful product, but the same lifetime updates and support I offer on all my premium addons. By contrast, the free version of TaigaChat is largely unsupported - all future updates will be channelled into TaigaChat Pro. You are also buying into tried and tested technology - TaigaChat was one of the first major XenForo addons and has existed since the first beta versions of XenForo, with constant updates ever since.
In moving from the free version to TaigaChat Pro on my live forum, the activity of the shoutbox has drastically increased. Factors such as the new 'speed mode' refresh system and persistent message colouring have given it the 'XenForo Effect'; it is simply more fun to use. Of course, standard forum posting has not decreased - on the vast majority if not all forums, shoutbox messages and forum posts are used for entirely discrete purposes.