i use Maverick Model 3D
i dont think it can import .x but it can import .obj and convert to .md3
i am pretty n00bish when it comes to 3d modelling. i did the same path though, misfit didnt work, and some research popped up maverick as a fork, and it works for me. but i also haven't used it for complex stuff. i don't know anything about merging meshes, wrapping/unwrapping uvs or any of that stuff. i know that those are things, that's the limit of my knowledge :)