When I was using Adobe Test and Target, it was solely within the marketing department primarily for the sake of quick tests that only really involved HTML, CSS or JS changes. We would use it to test hiding something or switching something to a different image or different text. This testing solution was not leveraged for larger test initiatives like full page redesigns or testing new feature sets. It was great for what we used it for, which may have been only 20% of what the tool had to offer, but a home grown testing platform worked better and was easier to manage for the larger stuff. With that being said, what we used it for on a regular basis just didn't justify the cost of the solution. Being a relatively Adobe shop, I got sick of the 'Adobe Promise' of it integrates perfectly with your other Adobe solutions and products. They all talk and work well together.... or so they say. I worked on three different Adobe product integrates; one was relatively simple, but the other two were jokes.