I can't say much for Talend. However, I was at a user group meeting here in Columbus at Cardinal Health. Cardinal Health gathers all their data from various servers throughout their company. They have many divisions with entirely different data systems. Yet Alteryx seems to be able cross the various systems, put the data in a standard format and then hand it to Tableau.They have thousands of Tableau users and are growing the user base substantially. Almost nobody gets Excel reports any more and their business analysts spend more time actually analyzing vs preparing reports. The Alteryz interface was very graphical and covered a wide set of data formats. It was more like setting up data pipes on a screen and connecting them together to get what you needed. Its not cheap but it seems to make up for that by allowing you to develop your data connections quickly. Its quite impressive. I wish I could help you more, but I thought you might want to hear about someone who is extremely successful using Alteryx with Tableau. If I can find the info for one of the contacts at Cardinal Health, I'll relay it to you. We haven't had a meeting in quite some time.
Thanks for your insights.