Naw, that was jest me messing it up. I had to change the default BRF opener to try and open one of the old BRFs, so of course when I tried to open new ones it phailed.
Anyways, it works perfectly. The only thing is you can't import more than one resource type at a time, so you need to import all the meshes, then save it and import it to the new one, then all the materials, then textures etc.