We probably need a someone in the community with more Smallworld experience to chime in regarding Smallworld dimensions. I know that in the past we have configured FME to extract dimensions from Smallworld to AutoCAD. The Smallworld 5.1 documentation mentions that dimension geometry cannot be exported, but I suspect that some magik configuration would turn that around. In older versions of Smallworld, I think how the dimensions had been configured would dictate if they could be accessed by FME.

Regarding Geodatabase: FME can write to dimension geometries, see the FME user documentation, and the section on Dimensions