What is the suggested workflow is for working with 3DS=>Unity via FBX files?
If I update the FBX file and reimport in Unity, it's not the same as deleting the re-adding the FBX in Unity.
Deleting and re-adding works as one would expect, but this means any changes I've made to the prefab have to be redone (split animations, loop settings, removing erroneous geos, etc) - all links are lost etc; so this isn't a feasible workflow.
The simplest case right now is changing a texture. If I change a texture, overwrite the FBX file, and reimport it in Unity; it doesn't get updated. However, if I create a new prefab from that FBX file; the textures are the updated ones in the new prefab created by Unity.
So generally, what is the suggested workflow here? Why doesn't overwriting FBX files work as one would expect?
Texture changes are not expected to work. It's by design. The idea is once you import model Unity creates materials and it doesn't overwrite them afterwards. It's done that way, because we want to allow users to edit their materials in Unity (setup right shader and so on) and we don't want to overwrite all that work when mesh is changed.
Meshes and animations should change as expected by just overwriting the file.
Regarding prefabs it's a known problem (i.e. if you add additional objects to the file they do not appear in the prefab). We have plans to improve our prefab system and these problems should be fixed then.
So to summarize: you should be overwriting your FBX files and it should work. If something doesn't - we want to know.
It is my goal to touch FBX content files as little as possible in Unity. It is imperative that the workflow for me be smooth and seamless into Unity from Max.
The simple solution. Change a Max material, change its name and Unity is forced to pick up the change when you introduce the new FBX.
Also, simply over-writing FBX files already in the Assets dir seems to sometimes be problematic. Particularly if you already have them under source control. I export them to a separate temp dir and then copy them into Assets. Seems to produce more consistent and desirable results.