Since dim3 has the ability to export to FBX you must be able to get into Maya with no problem.
Since I not have the software I’m not be able to test but looking at the features of the software, I think that’s the way
About poser, I suggest you to not use poser meshes, the have a lot of polygons, but, if you want, try with Reiss Studio software, the plug in exports poser to Maya. Then you can send to unity with no problems.