with blender's split edge modifier (which allows hard/soft edge workflow like in maya for example) you don't need detours for getting hard model edges. except if blender is a detour for you.

i don't believe that irrlicht is much faster than gamestudio. irrlicht uses a simple octree, gamestudio uses an ABT tree which is quite similar. because the map compiler doesn't really work for meshes at the moment, people often use single models for whole levels which don't get split up then by the ABT tree. so (like in the venice demo) there will be no frustum culling and no front to back sorted drawing.

the map compiler is a problem. i think conitec should just release the specifications of the wmb format. then maybe (i don't know how complex the wmb format is) a blender exporter which completely gets rid of the need for a level compiler could be done quite easily.