I created a couple of scripts for this specifically you can use for free if you like. You can alter them to do some more things its in the readme how to do this. Ill expand on this next year but at the moment I made it just for my workflow - basic vray roughness -> fbx then on convert the materials to either vray or corona in c4d.
At the moment I think there is an issue with the metalness (when not using a metal texture and metal using numeric value only), its on my to do list but otherwise should do the trick when using metal bitmaps. If you have 2sided vray materials it will use the front material,
also on my to do list is convert the color-correct nodes as if its being used it will ignore these materials for now (keep as vray mat).Script is now updated with Metal numeric values working, Color Correction & Falloff nodes will be replaced with the diffuse texture. Also works with multi-sub materials (any depth) since its just looking for Vray Classes. You can add your own Vray classes at the bottom (read the --notes). You can reference the Vray2SidedMtl class to see how to add your own its quite simple to do so if you have some basic coding experience.
Convert from 3dsmax Vray -> FBX
https://github.com/jmdvella/3dsmax-scriptsConvert FBX -> C4D (Corona/Vray)
https://github.com/jmdvella/cinema4d-scriptsFeel free to give me some feedback, or you can edit the scripts to suit some specific things in your workflow if you know some basic python/maxscript.