First save the Revit file to IFC format. Use Archicad merge. Goto file, then interoperability. And you will see merge. Then choose the IFC file. And click ok
I dont think you are 'converting' from Revit to Archicad but 'switching'. Im Revit user for 8 years but now im all with Archicad. Without a doubt Revit is good for engineer, but not for me ( architect and designer ) because Revit model ugly. Revit fail when come to finishing part such as detail roof model, kitchen, stairs, railing etc. Importing Revit's model to Sketchup or Blender look so ugly, triangulate faces and it doesnt impress at all. But importing models from Archicad to Sketchup or Blender will look very impressive. Very detail 3D roof ( not texture ), with neat valley cut, barge, fascia, guttering and down pipes. Share with me your workflow and let me know if Revit can do better in term of modelling design.
