Both the Freemium model and the Free Trial model require a lot of people at the top of the funnel. Speaking from what I've heard from friends (Squarespace, Harvest, etc.) who use the Free Trial is that they require the same amount of users at the top of the funnel as the Freemium model. The main difference is that they only have to support 1 version of their web app instead of a segmented free and paid version. This means you don't have to think about segmenting features, supporting free users, etc.