We use Everhour as our central tool for measuring time spent on projects and tasks. Furthermore we use its capabilities for exports of overviews and analysis. Even our regular working time is collected with Everhour.
I cannot provide any hard numbers regarding ROI, since we use Everhour to measure other things. But, if we would write down our work-time or collect it with any other tool lacking export features, at least 30 min / month would be needed to process this data.
Compared with the cost, there obviously is a direct return.
We used Harvest before, but it lacks a (good) automated and continuous import of our Asana projects. This was the primary reason for switching. Another reason were the more suitable exports Everhour can create.