Decompiling a map usually lost some aspects: detail brushes, lights and texture alignment for example (it lost more things I believe)...
And the q3map2 versions that came with Gtk can decompile too.
"C:\Program Files\GtkRadiant 1.5.0\q3map2" -convert -v -game tremulous -fs_basepath "C:\Program Files\Tremulous" -fs_game base -format map "C:\Program Files\Tremulous\base\maps\YourMapName.bsp"