Hi,
Acknex is built to take advantaje of the BSP tree. It uses ABT when BSP is missing. With a full control of LOD stages of meshes and materials you can build a reasonably large and detailed scenery with no BSP for a FPS but far from the open worlds seen in the game market, you know. Its workflow is like Source engines one but worse. Take advantaje of the BSP tree means that you must cut the scenery in closed halls and connect them by leaf cuts, all built with WED blocks and portals. This main workflow is in front to front to the open world concept. In any case you can certainly go out of the box and help the engine to minimize the draw calls and memory usage by merging or reusing stuff by yourself. You can try a test I did with a terrain, but real time procedural terrains do not collide, so it needs another workaround and so and so... Acknex is an ancient engine and its tools are from the first yeas of the century, that is a fact. It is many steps behind Unreal, in almost a couple of decades laugh Don't espect high compability. FBX2010 is the key.

Salud!