Thanks Greg, Yes I see Fbx does work in general but not from the latest version of speedtree in my tests up to now. I can take the speedtree fbx to polytrans and re-export to fbx and it will then import. Only problem seems to be the vertex count changing on import to EIAS for some reason. If I understand MDD correctly, it holds animation for each vertex/point in the mesh, so the mesh needs the same or maybe a very close vertex count.
The preview in Ei shows it working as it should, but only with a display of points. If the import would keep the vertex count from speedtree, this would be a very easy way to get fantastic moving trees.
Anyway, more tests I think!