I like doing large interior levels and using a standard 3d app is a long tedius process. I have 3d world studio and wondered how suitable it was for unity. I tried a small test level but the player moved very slowly compared to a similar level done in ac3d.
If it can export models and textures to common formats, there is no reason for it to not work with Unity.
Depending on export options it provides, you could also write your own import script in Unity if you wish.
If the only problem is movement speed, thats a matter of simply changing one or two variables.
Thanks. 3dws has x exporter but I can use ultimate unwrap to convert to obj or fbx.