@Marcus :
Results of my recent experiments about the Relinking trouble :
I exported exactly the same scene (takes 1047MB of VRAM in Octane) in Blender 2.49b with the old exporter, and in Blender 2.59 with the recent one made by Yoyoz.
I exported my original scene, and the modified scene (to be relinked)with just a textured plane added and an unwanted object removed, exactly in the same conditions as previously. So I exported four obj/mtl couples : from 2.49b, from 2.59, original and modified for both.
I loaded the original scene in Octane 1.0beta2.52 from each export with success, but failed to relink the modified obj, whatever the exporter used.
Then, I did exactly the same with the same files in Octane1.0246 Cuda 3.0 version, and it relinked fine, whatever the exporter used.
I loaded the ocs file made in 1.0246 from Blender 2.59 in Octane 1.0247 before relinking, and tried to relink the modified obj in 1.0247 : No crash, but the relinking is not completed : The name of the obj has changed to the relinked one, and the added object appear in the Outliner (not in the materials), but is absent in the render view. On the opposite, removed object is still present in the render view !
- Then, I create a new scene, and I load the original obj instead of opening the ocs file created in 1.0246, and the result when relinking looks at first glance the same. I have the idea of selecting the plane added (with alpha, because it is an UV mapped cloud of smoke). As I don't see it, I delete the alpha image in the material. I get the template sphere for material. I click on the mesh node to get rid of it, and after a second, the render view refreshes, showing the smoke, and the unwanted object of the previous obj has disappeared !
- I tested as well in 1.0248 and it relinks fine automatically, without any trouble.
- I tested as well in 1.0249b and it relinks fine automatically, without any trouble.

DAMNED ! I was going to repeat the tests in 1.0250 and 1.0251 (I have never used these versions), when I had the idea of trying again in 1.0beta2.52 before, and this time relinking worked. This said, the Blender scene is the same, but the obj file is a new export. Maybe something weird occured in the initial obj...
Well, I have to setup all my materials again, and I hope that this very annoying problem will not come back again when I will relink my next increased obj file !

I noticed (and reported in the plugins section) that with exactly the same settings, the Addon exporter for 2.59 gives an export time more than twice longer than the old script for Blender 2.49 : In my current scene, the export time is 3 min 40 s with the old script and 7 min 52 s with the Addon for 2.59 !

French Blender user - CPU : intel Quad QX9650 at 3GHz - 8GB of RAM - Windows 7 Pro 64 bits. Display GPU : GeForce GTX 480 (2 Samsung 2443BW-1920x1600 monitors). External GPUs : two EVGA GTX 580 3GB in a Cubix GPU-Xpander Pro 2. NVidia Driver : 368.22.