Trenchbroom is what one would call a radiant/quake like editor, it feels much more intuitive, more like working in a 3d programm....
but yaa should try it for urself.
make sure you Download Trenchbroom 2
supported platforms are:
Mac OS X
Linux DEB Packages
Linux RPM Packages
Now what could one do with it for T3D, well create your level, export it as .obj and get it into your fav 3dapp, the imported .obj is clean and you can create modular environments or simply the ground work for your level in trenchbroom.
Post some pics of your Trenchbroom to T3D work,
thanks and cya