A study from Jonkoping University.
From the library perspective MetaLib/SFX offers a single point of entry for multiple library resources, and MetaLib/SFX are updated centrally, which is much easier than local libraries trying to keep track of the all available resources.
The study was based on a series of workshops with library staff, and how they expected it to affect their work, and with end-users of MetaLib.
The study was qualitative, but it seemed to indicate that MetaLib resulted in better exposure of all available resources, but the end-users find it difficult to interact with MetaLib.