What is the purpose of doing that? It's a lot more effort than is necessary considering how little detail there actually is and how unlikely anyone is to notice it during gameplay.
had a idea and wanted to try it out, the most essential; in a early stage to see if it would work to have players running on static mesh without having collision issues,
the subtle effect I'm after is having sand, dirt or snow gathering in the cracks between the stones and in corners, in addition to break up the tiling and get rid of sharp edges near "L"-shapes (i.e where wall meets floor),
the goal is to keep this effect subtle enough to not distracted players or to hinder gameplay, yet adding a level of detail that blends in naturally,
the only performance change I've seen is increased fps in some areas after replacing bsp with meshes, that was no surprise, but will continue to test hot spots as development continues, the big tile is 512 polys over 256x256 units with a 1024x1024 texture, it can be lodded down to ~40 polys which will save ~2-3k polys in some areas,
its a little bit more effort doing it like this, but thats what makes it fun